text:
The long-range effect in 6 H-SiC under irradiation with Xe ions
NASA Astrophysics Data System (ADS)
Kalinina, E. V.; Chuchvaga, N. A.; Bogdanova, E. V.; Skuratov, V. A.
Results of an electrical study of the "long-range effect" in 6 H-SiC crystals under irradiation with 167 MeV heavy Xe ions at fluences of 4 × 109 to 7 × 1011 cm-2 are reported for the first time. Structures with Schottky barriers formed on the C face of the crystals have been studied. The structures were irradiated in the same modes on the barrier and base (Si face) sides. Electrical procedures revealed for the first time the effect of a deep penetration of radiation defects to a depth several tens of times the range of Xe ions. It was found that radiation defects of the acceptor type are formed at the beginning of the range of Xe ions, whereas radiation defects of the donor type appear at the end of this range.
Teflon impregnated anatase TiO2 nanoparticles irradiated by 80 keV Xe+ ions
NASA Astrophysics Data System (ADS)
Khanam, Rizwin; Paul, Nibedita; Kumar, P.; Kanjilal, D.; Ahmed, Gazi A.; Mohanta, Dambarudhar
We report the effect of 80 keV Xe+ ion irradiation on the morphological and optical responses of TiO2 nanoparticles spread over commercially available polytetrafluoroethylene (PTFE, Teflon). These nanoparticles were synthesized via a convenient, sol-gel approach with titanium isopropoxide as the main precursor. From X-ray diffraction (XRD) studies we found that, the nanoparticles crystallize in anatase phase and with a preferential orientation of crystallites along (1 0 1) plane. Upon irradiation at a fluence of 1.25 × 1017 ions/cm2, the nanoparticle dimension was found to increase from a value of ˜9 nm to ˜20-30 nm. Essentially, particle growth is predicted as a consequence of swelling behavior accompanied by the formation of Xe van der Waal crystals in isolated regions of nano-titania. Evidence of nanoripples was also witnessed on the surface of the irradiated nano-titania. The morphological evolution was assessed both by atomic force and transmission electron microscopies (AFM and TEM) independently. From the UV-Vis optical absorption studies, the estimated optical band gap was found to drop with increasing fluence, while refractive index exhibited a remarkable improvement. Photoluminescence (PL) studies have revealed that, the band edge emission and those due to the self trapped excitons (STE) and other oxygen vacancy related ones were manifested considerably as a result of Xe ion irradiation.
Single crystals of magnesium-aluminate spinel MgAl{sub 2}O{sub 4} were irradiated with 340 keV Xe{sup 2} ions at {minus}173 C ({approximately} 100 K). A fluence of 1 x 10{sup 20} Xe/m{sup 2} created an amorphous layer at the surface of the samples. The samples were annealed for 1 h at different temperatures ranging from 130 C to 880 C. Recrystallization took place in the temperature interval between 610 C and 855 C. Transmission electron microscopy (TEM) images show two distinct layers near the surface: (1) a polycrystalline layer with columnar grain structure; and (2) a buried damaged layer epitaxial with the substrate. After annealing at 1100 C for 52 days, the profile of implanted Xe ions did not change, which means that Xe ions are not mobile in the spinel structure up to 1100 C. The thickness of the buried damaged layer decreased significantly in the 1100 C annealed sample comparing to the sample annealed for 1 h at 855 C.
Quasi-two-dimensional Ag nanoparticle formation in silica by Xe ion irradiation and subsequent Ag ion implantation
Wang, Jun; Jia, Guangyi; Mu, Xiaoyu [School of Science, Tianjin University, Tianjin 300072 (China)] [School of Science, Tianjin University, Tianjin 300072 (China); Liu, Changlong [School of Science, Tianjin University, Tianjin 300072 (China) [School of Science, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072 (China)
Ag nanoparticles were fabricated in silica by Xe ion irradiation and subsequent Ag ion implantation, which distributed in a depth range from 4.8 to 14.3 nm, rather than dispersed from surface to a depth of 24.7 nm when no irradiation was made in advance. In addition, the suppression of Ag implants' sputtering loss was also evidenced by a greatly increased Ag content in the prepared sample. These results are mainly due to the defect-enhanced in-beam particle growth. Further, formation of polycrystalline Ag nanoparticles was revealed, whose effect on optical absorption was discussed according to the electron mean-free-path mode.
Damage Accumulation in MgAl{sub 2}O{sub 4} and Yttria-Stabilized ZrO{sub 2} by Xe-Ion Irradiation
Afanasyev-Charkin, I.V.; Gritsyna, V.T.; Cooke, D.W.; Bennett, B.L.; Sickafus, K.E.
Magnesium-aluminate spinel (MAS) and yttria-stabilized zirconia (YSZ) are being considered for use as ceramic matrices in proliferation resistant fuels and radioactive storage systems, and may be used either as individual entities or as constituents in multicomponent ceramic systems. It is worthwhile, therefore, to compare radiation damage in these two potentially important materials when subjected to similar irradiation conditions, e.g., ion beam irradiation. To compare radiation damage properties of these two materials, single crystals of spinel and zirconia were irradiated with 340 keV Xe{sup ++} ions at 120 K, and subsequently investigated by Rutherford backscattering and ion channeling (RBS/C), and optical absorption spectroscopy. Results indicate that damage accumulation in both spinel and zirconia follow a three stage process: (1) very slow damage accumulation over a wide range of dose; (2) rapid changes in damage over a range of doses from about 0.25 to 25 displacements per atom (DPA); (3) slower damage accumulation at very high doses and possibly saturation. Optical absorption results indicate that F-centers form in Xe ion-irradiated spinel and that the concentration of these centers saturates at high dose. Absorption bands are also formed in both spinel and zirconia that are due to point defect complexes formed upon irradiation. These bands increase in intensity with increasing Xe dose, and, in the case of zirconia, without saturation. Finally the rate of change in intensity of these bands with increasing Xe dose, mimic the changes in damage observed by RBS/C with increasing dose.
Behavior of zirconia based fuel material under Xe irradiation
Degueldre, C. [Paul Scherrer Inst., Villigen PSI (Switzerland). Lab. of Material Behaviour; [Univ. of Geneva (Switzerland). Centre des Sciences de l`Environment; Heimgartner, P.; Ledgergerber, G. [Paul Scherrer Inst., Villigen PSI (Switzerland); Sasajima, N. [Nagoya Univ., Chikusa, Aichi (Japan). Dept. of Quantum Engineering; Hojou, K.; Muromura, T. [Japanese Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Plutonium Rock-like Fuel Integrated R and D Team; Wang, L.; Gong, W.; Ewing, R. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences
The behavior of ZrO{sub 2}-10%YO{sub 1.5}-5%ErO{sub 1.5}-(10%ThO{sub 2}) (At %) cubic solid solutions under low and high energy Xe ion irradiation up to a fluence of 1.8 {center_dot} 10{sup 16} Xe-cm{sup {minus}2} was investigated by TEM. Low energy (60 keV) Xe ions did not yield amorphization. From the observed bubble formation, swelling values of less than one volume percent were estimated to be 0.19--0.72% during irradiation at room temperature or at high temperature (925 K). Furthermore, no amorphization was obtained by Xe irradiation under extreme conditions such as high energy (1.5 MeV) Xe ion and low temperature (20 K). This confirms the robustness of this material and argues in favor of the selection of zirconia based material as an advanced nuclear fuel for plutonium disposition.
Influence of Xe2+ ions on the micro-hollow cathode discharge driven by thermionic emission
NASA Astrophysics Data System (ADS)
Levko, D.; Bliokh, Y. P.; Krasik, Ya. E.
The influence of Xe2+ dimer ions and excited Xe* atoms on the hollow cathode discharge driven by electron thermionic emission is studied using two-dimensional Particle-in-Cell Monte Carlo Collisions modeling. A comparison with the results of two-component (electrons and Xe+ ions) plasma modeling showed that the presence of the Xe2+ dimer ions and excited Xe* atoms in the plasma affects the plasma parameters (density, potential, and ion fluxes toward the cathode). The influence of Xe2+ ions and Xe* atoms on the plasma sheath parameters, such as thickness and the ion velocity at the sheath edge, is analyzed.
Surface Morphology and Phase Stability of Titanium Foils Irradiated by 136 MeV 136Xe
Sadi, S; Loveland, W; Watson, P R; Greene, J P; Zhu, S; Zinkann, G
A stack of titanium foils was irradiated with 136 MeV 136Xe to study microstructure damage and phase stability of titanium upon irradiation. X- ray diffraction, scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy were used to study the resulting microstructure damage and phase stability of titanium. We observed the phase transfor- mation of polycrystalline titanium from alpha-Ti (hexagonally closed packed (hcp)) to face centered cubic (fcc) after irradiation with 2.2 x 1015 ions/cm2. Irradiation of Ti with 1.8 x 1014-2.2 x 1015 ions/cm2 resulted in the forma- tion of voids, hillocks, dislocation loops, dislocation lines, as well as polygonal ridge networks.
Surface Morphology and Phase Stability of Titanium Foils Irradiated by 136 MeV 136Xe
S. Sadi; A. Paulenova; W. Loveland; P. R. Watson; J. P. Greene; S. Zhu; G. Zinkann
A stack of titanium foils was irradiated with 136 MeV 136Xe to study microstructure damage and phase stability of titanium upon irradiation. X- ray diffraction, scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy were used to study the resulting microstructure damage and phase stability of titanium. We observed the phase transfor- mation of polycrystalline titanium from alpha-Ti (hexagonally closed packed (hcp)) to face centered cubic (fcc) after irradiation with 2.2 x 1015 ions/cm2. Irradiation of Ti with 1.8 x 1014-2.2 x 1015 ions/cm2 resulted in the forma- tion of voids, hillocks, dislocation loops, dislocation lines, as well as polygonal ridge networks.
Experimental ion mobility measurements in Xe-N2 mixtures
NASA Astrophysics Data System (ADS)
Garcia, A. N. C.; Neves, P. N. B.; Trindade, A. M. F.; Cortez, A. F. V.; Santos, F. P.; Conde, C. A. N.
In this paper we present the results for the ion mobility measurements made in gaseous mixtures of xenon (Xe) and nitrogen (N2) for low reduced electric fields (in the 15 Td to 30 Td range), at room temperature. The choice of reduced electric fields was guided by typical gaseous detector's demands. In the 0-100% range of Xe concentrations in the mixture, only one peak was observed which was attributed to Xe2+; in fact its mobility was found to follow Blanc's law. A typical time-of-arrival spectrum for 90% Xe and 10% N2 is shown. The reduced mobilities, obtained from the peaks, are calculated and presented in this paper.
Ion irradiation-induced anisotropic plastic deformation
Polman, Albert
.3 This thesis 14 2 Anisotropic plastic deformation of colloidal silica particles under 4 MeV Xe ion irradiation-dimensional colloidal crystals, nanolithography 109 9.4 Photonic crystals of shape-anisotropic colloidal silica in silica glasses 95 8.1 Introduction 96 8.2 Experimental 96 8.3 Results and analysis 98 8.4 Discussion 101
Xe/+/ -induced ion-cyclotron harmonic waves
NASA Astrophysics Data System (ADS)
Jones, D.
Xenon ion sources on an ejectable package separated from the main payload during the flights of Porcupine rockets F3 and F4 which were launched from Kiruna, Sweden on March 19 and 31, 1979, respectively. The effects of the xenon ion beam, detected by the LF (f less than 16 kHz) wideband electric field experiment and analyzed by using a sonograph, are discussed. Particular attention is given to the stimulation of the ion-cyclotron harmonic waves which are usually linked to the local proton gyro-frequency, but are sometimes related to half that frequency. It was found that in a plasma dominated by O(+) ions, a small amount (1-10%) of protons could cause an effect such that the O(+) cyclotron harmonic waves are set up by the hydrogen ions, the net result being the observation of harmonic emissions separated by the hydrogen ion gyro frequency.
Ion acceleration in Ar-Xe and Ar-He plasmas. II. Ion velocity distribution functions
Ioana A. Biloiu; Earl E. Scime
Ion velocity distribution functions (ivdfs) are investigated by laser induced fluorescence in Ar-Xe and Ar-He expanding helicon plasmas as a function of gas composition. In the case of Ar-Xe plasma, it was found that in the helicon source, both the Ar+ and Xe+ vdfs are unimodal. Their parallel speeds are subsonic and unaffected by changes in gas composition. At the
Microstructure evolution in Xe-irradiated UO2 at room temperature
L.F. He; J. Pakarinen; M.A. Kirk; J. Gan; A.T. Nelson; X.-M. Bai; A. El-Azab; T.R. Allen
In situ Transmission Electron Microscopy was conducted for single crystal UO2 to understand the microstructure evolution during 300 keV Xe irradiation at room temperature. The dislocation microstructure evolution was shown to occur as nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation segments and tangles at higher doses. Xe bubbles with dimensions of 1-2 nm were observed after room-temperature irradiation. Electron Energy Loss Spectroscopy indicated that UO2 remained stoichiometric under room temperature Xe irradiation.
Ba-ion extraction from a high pressure Xe gas for double-beta decay studies T. Brunnera,
Gratta, Giorgio
Ba-ion extraction from a high pressure Xe gas for double-beta decay studies with EXO T. Brunnera investigating double-beta decay in 136 Xe. Efficient extraction and detection of Ba ions, the decay product of Xe, would allow for a background-free measurement of the 136 Xe double-beta decay. Keywords: RF
I-Xe dating - Intercomparisons of neutron irradiations and reproducibility of the Bjurbole standard
NASA Technical Reports Server (NTRS)
Hohenberg, C. M.; Kennedy, B. M.
Previously unpublished data from the stepwise heating analysis of the Valecitos 1 (V1) Bjurbole standard are presented together with the results of an isotopic dilution measurement of a KI monitor included in the V1 irradiation package. The results of these analyses are compared with the values observed in other irradiations. Apparent I-Xe 'formation' ages are reproducible for three different samples of Bjurbole, suggesting isotopic homogeneity for initial iodine in the bulk material. The systematics of neutron capture in Xe-135 (produced from U-235 neutron fission) are examined and verified in irradiated BCR-1.
Surface damage on 6H-SiC by highly-charged Xeq+ ions irradiation
NASA Astrophysics Data System (ADS)
Zhang, L. Q.; Zhang, C. H.; Han, L. H.; Xu, C. L.; Li, J. J.; Yang, Y. T.; Song, Y.; Gou, J.; Li, J. Y.; Ma, Y. Z.
Surface damage on 6H-SiC irradiated by highly-charged Xeq+ (q = 18, 26) ions to different fluences in two geometries was studied by means of AFM, Raman scattering spectroscopy and FTIR spectrometry. The FTIR spectra analysis shows that for Xe26+ ions irradiation at normal incidence, a deep reflection dip appears at about 930 cm-1. Moreover, the reflectance on top of reststrahlen band decreases as the ion fluence increases, and the reflectance at tilted incidence is larger than that at normal incidence. The Raman scattering spectra reveal that for Xe26+ ions at normal incidence, surface reconstruction occurs and amorphous stoichiometric SiC and Si-Si and C-C bonds are generated and original Si-C vibrational mode disappears. And the intensity of scattering peaks decreases with increasing dose. The AFM measurement shows that the surface swells after irradiation. With increasing ion fluence, the step height between the irradiated and the unirradiated region increases for Xe18+ ions irradiation; while for Xe26+ ions irradiation, the step height first increases and then decreases with increasing ion fluence. Moreover, the step height at normal incidence is higher than that at tilted incidence by the irradiation with Xe18+ to the same ion fluence. A good agreement between the results from the three methods is found.
Accurate Xe isotope measurement using JPL ion trap.
Madzunkov, Stojan M; Nikoli?, Dragan
We report an approach for the reproducible and accurate compositional analysis of different mixtures of Xe isotopes using miniature Jet Propulsion Laboratory Quadrupole Ion Trap (JPL-QIT). A major study objective was to validate the recent instrumental improvements to the long-term operational stability under different pressures, temperatures, and trapping conditions. We propose that the present device can be used in certification of trace amounts of isotopes in mixtures dominated by one or more isotopes. Measured isotopic compositions are verified against commercially available standards with accuracy better than 0.07%. To aid the analysis of experimental data, we developed a scalable replica fitting method and use peak areas as descriptors of relative isotopic abundances. This low-power and low-mass device is ideally suited for planetary explorations aimed to enhance quantitative analysis for major isotopes present in small amounts of atmospheric samples. PMID:25216693
Ion acceleration in Ar-Xe and Ar-He plasmas. II. Ion velocity distribution functions
Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)
Ion velocity distribution functions (ivdfs) are investigated by laser induced fluorescence in Ar-Xe and Ar-He expanding helicon plasmas as a function of gas composition. In the case of Ar-Xe plasma, it was found that in the helicon source, both the Ar{sup +} and Xe{sup +} vdfs are unimodal. Their parallel speeds are subsonic and unaffected by changes in gas composition. At the end of the source, the argon ivdf shows a bimodal structure indicative of an electric double layer upstream of the measurement location. The fast argon ion component parallel velocity increases with Xe fraction from 6.7 to 8 km/s as the Xe fraction increases from 0% to 4%. In the expansion region, the bimodal character of Ar ivdf is maintained with a supersonic fast component reaching parallel speeds of 10.5 km/s. For all the studied plasma conditions and different spatial locations, the Xe{sup +} vdf exhibits a unimodal structure with a maximum parallel flow velocity of 2.2 km/s at the end of the source. For Ar-He plasma, the Ar ivdf is bimodal with the fast ion component parallel velocity increasing from 5.2 to 7.8 km/s as the He fraction increases from 0% to 30%. For the same He fraction range, the slow argon ion population distribution changes from a single Gaussian to a wide distribution extending all the way from the speed of the fast population to 0 m/s.
Calculation of Ion Charge State Distributions After Inner-Shell Ionization in Xe Atom
Mohammedein, Adel M.; Ghoneim, Adel A.; Kandil, Kandil M.; Kadad, Ibrahim M. [Applied Sciences Department, College of Technological Studies, P.O. Box 42325, Shuwaikh 70654 (Kuwait)
The vacancy cascades following initial inner-shell vacancies in single and multi-ionized atoms often lead to highly charged residual ions. The inner-shell vacancy produced by ionization processes may decay by either a radiative or non-radiative transition. In addition to the vacancy filling processes, there is an electron shake off process due to the change of core potential of the atom. In the calculation of vacancy cascades, the radiative (x-ray) and non-radiative (Auger and Coster-Kronig) branching ratios give valuable information on the de-excitation dynamics of an atom with inner-shell vacancy. The production of multi-charged ions yield by the Auger cascades following inner shell ionization of an atom has been studied both experimentally and theoretically. Multi-charged Xe ions following de-excitation of K-, L{sub 1}-, L{sub 2,3}-, M{sub 1}-, M{sub 2,3}- and M{sub 4,5} subshell vacancies are calculated using Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger, Coster- Kronig yield (non- radiative) are evaluated. The decay of K hole state through radiative transitions is found to be more probable than non-radiative transitions in the first step of de-excitation. On the other hand, the decay of L, M vacancies through non-radiative transitions are more probable. The K shell ionization in Xe atom mainly yields Xe{sup 7+}, Xe{sup 8+}, Xe{sup 9+} and Xe{sup 10+} ions, and the charged X{sup 8+} ions are the highest. The main product from the L{sub 1}- shell ionization is found to be Xe{sup 8+}, Xe{sup 9+} ions, while the charged Xe{sup 8+} ions predominate at L{sub 2,3} hole states. The charged Xe{sup 6+}, Xe{sup 7+} and Xe{sup 8+} ions mainly yield from 3s{sub 1/2} and 3p{sub 1/2,3/2} ionization, while Xe in 3d{sub 3/2,5/2} hole states mainly turns into Xe{sup 4+} and Xe{sup 5+} ions. The present results are found to agree well with the experimental data.
Raman spectroscopic investigation of ion-beam-irradiated glassy carbon
S. Prawer; F. Ninio; I. Blanchonette
Raman spectroscopy has been used to monitor the changes induced in glassy carbon as a result of irradiation with H, He, C, N, Si, and Xe ions. The Raman spectrum of unirradiated glassy carbon consists of an intrinsic graphite peak at 1590 cm?1 (the a peak) and a disorder-induced D peak at 1350 cm?1. The G peak position and FWHM
Zirconium oxidation under high energy heavy ion irradiation N. Brerd, A. Chevarier, N. Moncoffre, H. Jaffrezic,
Paris-Sud XI, Université de
Zirconium oxidation under high energy heavy ion irradiation N. Bérerd, A. Chevarier, N. Moncoffre This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions on the oxidation kinetics of zirconium. This study is performed in the framework of long-term storage of nuclear
Ba-ion extraction from a high pressure Xe gas for double-beta decay studies with EXO
T. Brunner; D. Fudenberg; A. Sabourov; V. L. Varentsov; G. Gratta; D. Sinclair; for the EXO collaboration
An experimental setup is being developed to extract Ba ions from a high-pressure Xe gas environment. It aims to transport Ba ions from 10 bar Xe to vacuum conditions. The setup utilizes a converging-diverging nozzle in combination with a radio-frequency (RF) funnel to move Ba ions into vacuum through the pressure drop of several orders of magnitude. This technique is intended to be used in a future multi-ton detector investigating double-beta decay in $^{136}$Xe. Efficient extraction and detection of Ba ions, the decay product of Xe, would allow for a background-free measurement of the $^{136}$Xe double-beta decay.
Fully stripped heavy ion yield vs energy for Xe and Au ions
NASA Astrophysics Data System (ADS)
Thieberger, P.; Wegner, H. E.; Alonzo, J.; Gould, H.; Anholt, R. E.; Meyerhof, W. E.
The Bevalac is now capable of accelerating U-238 ions to approximately 1 GeV/amu and measurements have shown that fully stripped U-238 ions are produced with good yield at these energies. However, knowing the stripping yields at different energies for U-238 does not allow an accurate prediction for other, lower Z projectiles. Consequently, extensive stripping yield measurements were made for Au-197 and Xe-139 ions. In addition to the stripping measurements from the direct Bevalac beam, pickup measurements were also made with specially prepared bare, one electron, and two electron ions. Since many research groups are considering heavy ion storage rings and/or synchrotrons, the pickup cross section for bare ions is important to estimate beam lifetime in terms of the average machine vacuum. Since the Mylar target provides a pickup probability similar to air, a preliminary analysis of the Xe(54+) and U(92+) data are presented along with predictions for other ions ranging down to Fe(26+).
Observation of hyperfine mixing in measurements of a magnetic octupole decay in isotopically pure nickel-like 129Xe and 132Xe ions
Trabert, E; Beiersdorfer, P; Brown, G V
We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2) radiation.
Observation of Hyperfine Mixing in Measurements of a Magnetic OctupoleDecay in Isotopically Pure Nickel-Like {sup 129}Xe and {sup 132}Xe Ions
Traebert, E.; Beiersdorfer, P.; Brown, G. V. [High Temperature and Astrophysics Division, Lawrence LivermoreNational Laboratory, Livermore, California 94550-9234 (United States)
We present measurements of high statistical significance of the rate ofthe magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotopewith zero nuclear spin and therefore without hyperfine structure, the lifetimeof the metastable level was established as (15.06{+-}0.24) ms. On {sup 129}Xe, an additionalfast (2.7{+-}0.1 ms) decay component was established that representshyperfine mixing with a level that decays by electric quadrupole (E2) radiation.
Ion mobilities in Xe/Ne and other rare-gas mixtures
NASA Astrophysics Data System (ADS)
Piscitelli, D.; Phelps, A. V.; de Urquijo, J.; Basurto, E.; Pitchford, L. C.
The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this cross section set in a Monte Carlo simulation are reported for reduced field strengths, E/N, up to 1500×10-21 V m2, in pure gases and in Xe/Ne mixtures containing 5% and 20% Xe/Ne, which are mixtures of interest for plasma display panels (PDPs). The calculated Xe+ mobilities depend strongly on the mixture composition, but the Ne+ mobility varies only slightly with increasing Xe in the mixture over the range studied here. The mobilities in pure gases compare well with available experimental values, and mobilities in gas mixtures at low E/N compare well with our recent measurements which will be published separately. Results from these calculations of ion mobilities are used to evaluate the predictions of Blanc's law and of the mixture rule proposed by Mason and Hahn [Phys. Rev. A 5, 438 (1972)] for determining the ion mobilities in mixtures from a knowledge of the mobilities in each of the pure gases. The mixture rule of Mason and Hahn is accurate to better than 10% at high field strengths over a wide range of conditions of interest for modeling PDPs. We conclude that a good estimate of ion mobilities at high E/N in Xe/Ne and other binary rare gas mixtures can be obtained using this mixture rule combined with known values of mobilities in parent gases and with the Langevin form for mobility of rare gas ions ion in other gases. This conclusion is supported by results in Ar/Ne mixtures which are also presented here.
Topological and chemical investigation on super-hydrophobicity of PTFE surface caused by ion irradiation
Yan Chen; Ziqiang Zhao; Junfeng Dai; Yingmin Liu
Super-hydrophobic PTFE surfaces were obtained by irradiation of 200keV Xe+ ion with the fluence of 6.2×1013 ions\\/cm2. The contact angle of water on such surface is as large as 161±3°. SEM and XPS were used to investigate how the topological and chemical changes affect the wettability of the irradiated surface. Needle like structures at nanometer scale caused by irradiation are
Optima XE Single Wafer High Energy Ion Implanter
Satoh, Shu; Ferrara, Joseph; Bell, Edward; Patel, Shital; Sieradzki, Manny [Axcelis Technologies, Inc. 108 Cherry Hill Drive, Beverly, MA 01915 (United States)
The Optima XE is the first production worthy single wafer high energy implanter. The new system combines a state-of-art single wafer endstation capable of throughputs in excess of 400 wafers/hour with a production-proven RF linear accelerator technology. Axcelis has been evolving and refining RF Linac technology since the introduction of the NV1000 in 1986. The Optima XE provides production worthy beam currents up to energies of 1.2 MeV for P{sup +}, 2.9 MeV for P{sup ++}, and 1.5 MeV for B{sup +}. Energies as low as 10 keV and tilt angles as high as 45 degrees are also available., allowing the implanter to be used for a wide variety of traditional medium current implants to ensure high equipment utilization. The single wafer endstation provides precise implant angle control across wafer and wafer to wafer. In addition, Optima XE's unique dose control system allows compensation of photoresist outgassing effects without relying on traditional pressure-based methods. We describe the specific features, angle control and dosimetry of the Optima XE and their applications in addressing the ever-tightening demands for more precise process controls and higher productivity.
Precision frequency trimming of SAW and STW resonators using Xe+ heavy ion bombardment
Vladimir Shakirovich Aliev; I. D. Avramov
A method for precision frequency trimming of surface acoustic wave (SAW) and surface transverse wave (STW) based resonant devices using a Xe+ heavy ion bombardment technique is described. The devices are downtrimmed in frequency in an in-situ monitoring process by means of a Kaufmann type ion source that allows first a rough and then a fine frequency trimming with an
Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films
Yosuke Kimura; Jinhua Chen; Masaharu Asano; Yasunari Maekawa; Ryoichi Katakai; Masaru Yoshida
Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe23+ with fluences of 0, 3×106, 3×107, 3×108 and 3×109ions\\/cm2, followed by ?-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent
Ion acceleration in Ar-Xe and Ar-He plasmas. I. Electron energy distribution functions and ion composition
Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morganton, West Virginia 26506 (United States)
Electron energy distribution functions (eedf), ion production, and ion composition are studied in Ar-Xe and Ar-He expanding helicon plasmas. It was found that under the conditions of constant total flow rate, Xe, in addition to Ar, changes the eedf from Maxwellian-like to Druyvesteyn-like with a shortening of the high energy tail at {approx}15 eV. The electron temperature exponentially decreases from {approx}7 eV in pure Ar plasma to {approx}4 eV in pure Xe plasma. Xenon ions dominate the ion population for Xe filling fractions greater than 10%. The plasma density increases by {approx}15% with increasing Xe fraction. For an Ar-He plasma, increasing the helium fraction increases the electron temperature from {approx}7 eV in pure Ar plasma to {approx}14 eV for a He filling fraction of 80%. The plasma density drops by more than three orders of magnitude from 1.14x10{sup 11} cm{sup -3} to 6.5x10{sup 7} cm{sup -3}. However, the inferred ion densities indicate that even at a helium fraction of 80%, argon ions significantly outnumber helium ions.
Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures
Kushner, Mark
Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures Paul. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays sources using a xenon/iodine gas mixture are being investigated as a multiwavelength UV lighting source
RTE measurement with Xe52+ ions channeled in a Si crystal
S. Andriamonje; M. Chevallier; C. Cohen; N. Cue; D. Dauvergne; J. Dural; R. Genre; Y. Girard; R. Kirsch; A. L'Hoir; J. C. Poizat; Y. Quéré; J. Remillieux; D. Schmaus; M. Toulemonde
KLL resonant transfer and excitation (RTE) of 33-43 MeV\\/nucleon He-like Xe ions channeled along the axis of a thin Si crystal has been investigated in measurements of charge state distributions and of the resulting X-ray production. The resonance peaks obtained by the two methods are quite similar. The charge state measurements show that RTE appears, for well channeled ions, to
A setup for Ba-ion extraction from high pressure Xe gas for double-beta decay studies with EXO
Gratta, Giorgio
A setup for Ba-ion extraction from high pressure Xe gas for double-beta decay studies with EXO T. This technique is intended for use in a future multi-ton detector investigating double-beta decay in 136 Xe-free measurement of the 136 Xe double-beta decay. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Several
The mobilities of xenon ions in xenon and the derived charge transfer cross section for Xe+(2P3\\/2) ions in xenon
P. H. Larsen; M. T. Elford
A drift tube of the four-gauze Tyndall-Powell type has been used to obtain accurate mobility data for ground-state Xe+(2P3\\/2) ions, metastable Xe+(2P1\\/2) ions and molecular Xe2+\\/Xe3+ ions in xenon at room temperature (294.1+or-0.2K) over a wide E\\/N range (E is the electric field strength and N is the gas number density). The measurements were made at E\\/N values from 50
Defect controlled ferromagnetism in xenon ion irradiated zinc oxide
NASA Astrophysics Data System (ADS)
Satyarthi, P.; Ghosh, S.; Mishra, P.; Sekhar, B. R.; Singh, F.; Kumar, P.; Kanjilal, D.; Dhaka, R. S.; Srivastava, P.
We report evolution of magnetic properties in zinc oxide (ZnO) single crystals and polycrystalline films induced by 500 KeV xenon ion (Xe3+) irradiation. Room temperature ferromagnetism (RT-FM) behavior is observed in as deposited polycrystalline ZnO film and strength of FM enhances with ion fluence up to 2×1017 ions/cm2 and then decreases. However, RT-FM is not observed in ZnO single crystals even after irradiation with fluence up to 3.5×1017 ions/cm2. The X-ray diffraction (XRD) and Raman measurements of ZnO single crystal reveal slightly disordered hexagonal wurtzite structure after irradiation. However, as deposited and irradiated polycrystalline ZnO films indicate excessive lattice defects in the wurtzite structure. X-ray photoelectron spectroscopy (XPS) reveals that Zn vacancy/interstitial defects are absent in all samples, although oxygen vacancy lattice defects are present. Density of oxygen vacancies is much higher in as deposited and irradiated polycrystalline ZnO films as compared to single crystals. This seems to be the determining factor for the presence and absence of RT-FM in ZnO films and single crystals respectively. The observed FM behavior in as deposited and irradiated polycrystalline ZnO films is explained on the basis of spin split impurity band formation from singly and doubly occupied oxygen vacancies which initiates d0 ferromagnetism.
Measurement of a magnetic-dipole transition probability in Xe32+ using an electron-beam ion trap
Serpa, F. G.; Morgan, C. A.; Meyer, E. S.; Gillaspy, J. D.; Trabert, E.; Church, David A.; Takacs, E.
The transition probability for the 3d(4) D-5(2) <-- D-5(3) magnetic-dipole transition in Ti-like Xe (Xe32+) has been measured using an electron-beam ion trap. The unusually weak dependence of the transition energy on nuclear charge Z, and the fact...
Measurement of a magnetic-dipole transition probability in Xe32+ using an electron-beam ion trap
Serpa, F. G.; Morgan, C. A.; Meyer, E. S.; Gillaspy, J. D.; Trabert, E.; Church, David A.; Takacs, E.
The transition probability for the 3d(4) D-5(2) dipole transition in Ti-like Xe (Xe32+) has been measured using an electron-beam ion trap. The unusually weak dependence of the transition energy on nuclear charge Z, and the fact...
Electronic relaxai:ion of Xe,CI in gaseous and supercritical fluid xenon F. Okada"'and V. A. Apkarianb)
Apkarian, V. Ara
Electronic relaxai:ion of Xe,CI in gaseous and supercritical fluid xenon F. Okada"'and V. A in gaseous and supercritical fluid xenon up to 150 atm are reported. Clustering of the exciplex with Xe atoms
Ion energy distributions, electron temperatures, and electron densities in Ar, Kr, and Xe pulsed discharges
Shin, Hyungjoo; Zhu Weiye; Economou, Demetre J.; Donnelly, Vincent M. [Plasma Processing Laboratory, Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204-4004 (United States)
Ion energy distributions (IEDs) were measured near the edge of Faraday-shielded, inductively coupled pulsed plasmas in Ar, Kr, or Xe gas, while applying a synchronous dc bias on a boundary electrode, late in the afterglow. The magnitudes of the full width at half maximum of the IEDs were Xe > Kr > Ar, following the order of the corresponding electron temperatures in the afterglow, T{sub e}(Xe) > T{sub e}(Kr) > T{sub e}(Ar). The measured decays of T{sub e} with time in the afterglow were in excellent agreement with predictions from a global model. Measured time-resolved electron and positive ion densities near the plasma edge did not decay appreciably, even in the 80 {mu}s long afterglow. This was attributed to transport of ions and electrons from the higher density central region of the plasma to the edge region, balancing the loss of plasma due to diffusion. This provides a convenient means of maintaining a relatively constant plasma density in the afterglow during processing using pulsed plasmas.
Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I{sub 2} mixtures
Barnes, P.N. [Wright Laboratory, 2645 Fifth Street Ste 13, Wright-Patterson AFB, Ohio 45433-7919 (United States)] [Wright Laboratory, 2645 Fifth Street Ste 13, Wright-Patterson AFB, Ohio 45433-7919 (United States); Kushner, M.J. [Department of Electrical and Computer Engineering, University of Illinois, 1406 W. Green St., Urbana, Illinois 61801 (United States)] [Department of Electrical and Computer Engineering, University of Illinois, 1406 W. Green St., Urbana, Illinois 61801 (United States)
Xe/I{sub 2} low-pressure electric discharges are being developed as efficient, long-lived ultraviolet lighting sources. In this work the kinetics of low pressure, 0.5{endash}5 Torr, radio-frequency inductively excited discharges sustained in Xe and I{sub 2} were investigated to determine the source of radiating states. The diagnostics applied in this study include optical absorption and emission spectroscopy, microwave interferometry, and microwave absorption. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays with time constants of hundreds of microseconds. These observations are consistent with those states being populated by ion-ion neutralization. Electron-ion recombination leading to excited states appears not to be an important source of emission.
Valence-shell photoionization of Ag-like Xe$^{7+}$ ions : experiment and theory
Mueller, A; Esteves-Macaluso, D; Habibi, M; Aguilar, A; Kilcoyn, A L D; Phaneuf, R A; Ballance, C P; McLaughlin, B M
We report on experimental and theoretical results for the photoionization of Ag-like xenon ions, Xe$^{7+}$, in the photon energy range 95 to 145~eV. The measurements were carried out at the Advanced Light Source at an energy resolution of $\\Delta$E = 65 meV with additional measurements made at $\\Delta$E = 28 meV and 39 meV. Small resonance features below the ground-state ionization threshold, at about 106 eV, are due to the presence of metastable Xe$^{7+} (4d^{10} 4f~^2{\\rm F}^{\\circ}_{5/2,7/2})$ ions in the ion beam. On the basis of the accompanying theoretical calculations using the Dirac Atomic R-matrix Codes (DARC), an admixture of only a few percent of metastable ions in the parent ion beam is inferred, with almost 100\\% of the parent ions in the $(4d^{10}5s ~^2{\\rm S_{1/2}})$ ground level. The cross-section is dominated by a very strong resonance associated with $4d \\rightarrow 5f$ excitation and subsequent autoionization. This prominent feature in the measured spectrum is the $4d^95s5f ~^2{\\rm P}^{\\cir...
Production of highly charged ion beams Kr32+, Xe44+, Au54+ with Electron String Ion Source (ESIS) Krion-2 and corresponding basic and applied studies
D. E. Donets; E. D. Donets; E. E. Donets; V. V. Salnikov; V. B. Shutov
Electron String Ion Source (ESIS) Krion-2 (JINR, Dubna) was used for basic and applied research in various aspects of multiply charged heavy ions production. Energy recuperation mode in ESIS has been proofed first and used for production of highly charged ions 84Kr28+÷84Kr32+, 124Xe40÷124Xe44 and Au51+÷ Au54+. Krion-2 ESIS was mounted on high voltage (HV) platform of LU-20 Linac and used
Photoionization Cross Section of Xe+ Ion in the Pure 5p5 P3/22 Ground Level
NASA Astrophysics Data System (ADS)
Thissen, R.; Bizau, J. M.; Blancard, C.; Coreno, M.; Dehon, C.; Franceschi, P.; Giuliani, A.; Lemaire, J.; Nicolas, C.
Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe+ ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20 23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe+ with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.
Raman study of apatite amorphised with swift heavy ions under various irradiation conditions
Christian Weikusat; Ulrich A. Glasmacher; Beatrice Schuster; Christina Trautmann; Ronald Miletich; Reinhard Neumann
Crystallographically oriented Durango fluorapatites were exposed to swift heavy ions (Xe, Ta, Au, U) at different irradiation\\u000a conditions. Beam-induced sample modifications were investigated with respect to the effect of fluence (109–1013 ions\\/cm2), electronic energy loss (18–27 keV\\/nm), and pressure (3.6–11.5 GPa) applied during irradiation. In situ high-pressure irradiation\\u000a was performed in diamond anvil cells. Confocal Raman spectroscopy was used to trace the
Heavy ion irradiation induced effects in Ni 3N\\/Al bilayers
S. Dhar; L. Rissanen; K. Engel; M. Wenderoth; K. P. Lieb
The article reports on the Xe ion beam irradiation studies of Ni3N\\/Al bilayers at 80 K. The ion-induced modifications were monitored by Rutherford backscattering (RBS), resonant nuclear reaction analysis (RNRA), X-ray diffraction (XRD) and atomic force microscopy (AFM). We found preferential loss of nitrogen from the surface region of the Ni3N top layers. The surface roughness ??S and the interface
Energies and transition rates for Be-like ions (Xe LI - Ce LV)
NASA Astrophysics Data System (ADS)
El-Sayed, Fatma; Khered, Manal; Attia, S. M.
Energy levels, wavelengths, oscillator strengths, transition probabilities and lifetimes have been calculated for Be-like Xe, Cs, Ba, La, and Ce ions among the fine-structure levels of terms belonging to the 2s2, 2s2p, 2p2, 2s3s, 2s3p, 2s3d, and 2p3d configurations. The calculations have been performed using the fully relativistic multiconfiguration Dirac-Fock (MCDF) method, taking the quantum electrodynamic corrections (QED) into account. The results are compared with the available other theoretical results.
An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe.
Twelker, K; Kravitz, S; Montero Díez, M; Gratta, G; Fairbank, W; Albert, J B; Auty, D J; Barbeau, P S; Beck, D; Benitez-Medina, C; Breidenbach, M; Brunner, T; Cao, G F; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Daugherty, S J; Davis, C G; DeVoe, R; Delaquis, S; Didberidze, T; Dilling, J; Dolinski, M J; Dunford, M; Fabris, L; Farine, J; Feldmeier, W; Fierlinger, P; Fudenberg, D; Giroux, G; Gornea, R; Graham, K; Hall, C; Heffner, M; Herrin, S; Hughes, M; Jiang, X S; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Krücken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Leonard, F; Licciardi, C; Lin, Y H; MacLellan, R; Marino, M G; Mong, B; Moore, D; Odian, A; Ostrovskiy, I; Ouellet, C; Piepke, A; Pocar, A; Retiere, F; Rowson, P C; Rozo, M P; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tosi, D; Vuilleumier, J-L; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Yang, L; Yen, Y-R; Zhao, Y B
We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product. PMID:25273779
An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe
NASA Astrophysics Data System (ADS)
Twelker, K.; Kravitz, S.; Díez, M. Montero; Gratta, G.; Fairbank, W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Beck, D.; Benitez-Medina, C.; Breidenbach, M.; Brunner, T.; Cao, G. F.; Chambers, C.; Cleveland, B.; Coon, M.; Craycraft, A.; Daniels, T.; Daugherty, S. J.; Davis, C. G.; DeVoe, R.; Delaquis, S.; Didberidze, T.; Dilling, J.; Dolinski, M. J.; Dunford, M.; Fabris, L.; Farine, J.; Feldmeier, W.; Fierlinger, P.; Fudenberg, D.; Giroux, G.; Gornea, R.; Graham, K.; Hall, C.; Heffner, M.; Herrin, S.; Hughes, M.; Jiang, X. S.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Leonard, F.; Licciardi, C.; Lin, Y. H.; MacLellan, R.; Marino, M. G.; Mong, B.; Moore, D.; Odian, A.; Ostrovskiy, I.; Ouellet, C.; Piepke, A.; Pocar, A.; Retiere, F.; Rowson, P. C.; Rozo, M. P.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Tosi, D.; Vuilleumier, J.-L.; Walton, J.; Walton, T.; Weber, M.; Wen, L. J.; Wichoski, U.; Yang, L.; Yen, Y.-R.; Zhao, Y. B.
We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope 136Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.
Theoretical investigation of HNgNH3(+) ions (Ng = He, Ne, Ar, Kr, and Xe).
Gao, Kunqi; Sheng, Li
The equilibrium geometries, harmonic frequencies, and dissociation energies of HNgNH3(+) ions (Ng = He, Ne, Ar, Kr, and Xe) were investigated using the following method: Becke-3-parameter-Lee-Yang-Parr (B3LYP), Boese-Matrin for Kinetics (BMK), second-order Møller-Plesset perturbation theory (MP2), and coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)). The results indicate that HHeNH3(+), HArNH3(+), HKrNH3(+), and HXeNH3(+) ions are metastable species that are protected from decomposition by high energy barriers, whereas the HNeNH3(+) ion is unstable because of its relatively small energy barrier for decomposition. The bonding nature of noble-gas atoms in HNgNH3(+) was also analyzed using the atoms in molecules approach, natural energy decomposition analysis, and natural bond orbital analysis. PMID:25877572
Theoretical investigation of HNgNH3+ ions (Ng = He, Ne, Ar, Kr, and Xe)
NASA Astrophysics Data System (ADS)
Gao, Kunqi; Sheng, Li
The equilibrium geometries, harmonic frequencies, and dissociation energies of HNgNH3+ ions (Ng = He, Ne, Ar, Kr, and Xe) were investigated using the following method: Becke-3-parameter-Lee-Yang-Parr (B3LYP), Boese-Matrin for Kinetics (BMK), second-order Møller-Plesset perturbation theory (MP2), and coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)). The results indicate that HHeNH3+, HArNH3+, HKrNH3+, and HXeNH3+ ions are metastable species that are protected from decomposition by high energy barriers, whereas the HNeNH3+ ion is unstable because of its relatively small energy barrier for decomposition. The bonding nature of noble-gas atoms in HNgNH3+ was also analyzed using the atoms in molecules approach, natural energy decomposition analysis, and natural bond orbital analysis.
Radiation tolerance of nanostructured ZrN coatings against swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Janse van Vuuren, A.; Skuratov, V. A.; Uglov, V. V.; Neethling, J. H.; Zlotski, S. V.
Nano-structured zirconium nitride layers - on Si substrates - of various thicknesses (0.1, 3, 10 and 20 ?m) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 3 × 1012 to 2.6 × 1015 cm-2 for Xe, 1 × 1013 to 7.06 × 1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of these irradiation experiments is to simulate the effects of fission fragment bombardment on nanocrystalline ZrN. The irradiated layers where subsequently analysed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nano-indentation hardness testing (NIH) techniques. XRD, TEM and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation.
Grain growth and phase formation in ion irradiated/annealed thin Ni-Al alloys films
Alexander, D.E.; Was, G.S. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Nuclear Engineering); Rehn, L.E. (Argonne National Lab., IL (USA))
Ion irradiation and annealing studies were performed on Ni, Ni-20 at.%Al multilayers and Ni-20 at.%Al co-evaporated thin films. Xe{sup +} ions were used to irradiate the films and homogenize the multilayers at room temperature. Irradiation of alloy films formed a metastable, supersaturated solid solution of {gamma} phase and an HCP phase. Ion induced grain growth occurred in all films. A factor of 2 greater growth was observed in Ni--Al multilayers compared with coevaporated films irradiated to the same dose. The enhancement is attributed to a heat of mixing effect. Post irradiation annealing of the mixed multilayers formed {gamma}{prime}, the morphology of which was dependent upon the presence of Cu in the films due to substrate mixing from the support grid. 10 refs., 1 fig.
Effects of ion irradiation on solid oxide fuel cells
NASA Astrophysics Data System (ADS)
Cheng, Jeremy
The solid oxide fuel cell (SOFC) is an electrochemical device that converts chemical to electrical energy. It is usually based around an oxide conducting ceramic electrolyte that requires temperatures above 800°C to operate. There are many advantages to lowering this operation temperature such as more gas sealing options and more efficient startup. One of the key limitations is in the transport of ions across the electrolyte. The most common electrolyte material used is Yttria-Stabilized Zirconia (YSZ). The ionic conductivity can be greatly affected by grain boundaries, dislocations, and point defects. In this study, dislocations were introduced by heavy ion irradiation. Irradiation with Xe+ or Ar+ produced a large number of point defects and dislocations via a mechanism similar to Frank partial dislocation formation. The dislocation density was on the order of 1012/cm2 and the Burgers vector was 1/2<110>. Heat treatment at temperatures from 800-1400°C changed the defect structure, eliminated point defects, and allowed dislocations to react and grow. Thin films of YSZ were deposited on silicon substrates using pulsed laser deposition (PLD). Films deposited on a metallized substrate were polycrystalline while films deposited directly onto conductive silicon could be epitaxially grown. Ion irradiation caused the film conductivity to drop by a factor of 2-3 due to additional point defects in the film. Heat treatment removed these point defects allowing the conductivity to recover. A novel method was developed to produce freestanding YSZ membranes without a silicon substrate by using the Focused Ion Beam (FIB). Thick, single-crystal YSZ pieces were thinned using in-situ X-Ray Energy Dispersive Spectroscopy (EDS) for end point detection. The final membranes were single crystal, less than 350nm thick, and pinhole free. IV curves and impedance measurements were made after irradiation and heat treatment. The conductivity showed similar trends to the PLD deposited thin films. In addition to the ohmic losses from the electrolyte, ion implantation also affected the activation losses of the electrode. Single crystal electrolytes were implanted with various species. The exchange current density improved by an order of magnitude following irradiation with Na+ and Xe+ on the cathode side.
Dose Control System in the Optima XE Single Wafer High Energy Ion Implanter
Satoh, Shu; Yoon, Jongyoon; David, Jonathan [Axcelis Technologies, Inc, 108 Cherry Hill Drive, Beverly, MA 01915 (United States)
Photoresist outgassing can significantly compromise accurate dosimetry of high energy implants. High energy implant even at a modest beam current produces high beam powers which create significantly worse outgassing than low and medium energy implants and the outgassing continues throughout the implant due to the low dose in typical high energy implant recipes. In the previous generation of high energy implanters, dose correction by monitoring of process chamber pressure during photoresist outgassing has been used. However, as applications diversify and requirements change, the need arises for a more versatile photoresist correction system to match the versatility of a single wafer high energy ion implanter. We have successfully developed a new dosimetry system for the Optima XE single wafer high energy ion implanter which does not require any form of compensation due to the implant conditions. This paper describes the principles and performance of this new dose system.
Precision frequency trimming of SAW and STW resonators using Xe(+) heavy ion bombardment.
Aliev, V S; Avramov, I D
A method for precision frequency trimming of surface acoustic wave (SAW) and surface transverse wave (STW) based resonant devices using a Xe(+) heavy ion bombardment technique is described. The devices are downtrimmed in frequency in an in-situ monitoring process by means of a Kaufmann type ion source that allows first a rough and then a fine frequency trimming with an accuracy of 1 ppm in a single continuous in-situ monitoring process. An improvement of the device insertion loss and unloaded Q as a result of the trimming process is achieved. Single mode 776 MHz STW resonators can be downtrimmed by more than 5000 ppm without deteriorating their parameters while SAW resonators allow a much lower frequency downshift. The method is simple and can cost effectively be applied to SAW and STW device fabrication. PMID:18263257
Ionization of He, Ne, Ar, Kr, and Xe by impact of He{sup +} ions
Miraglia, J. E.; Gravielle, M. S. [Instituto de Astronomia y Fisica del Espacio, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Casilla de Correo 67, Sucursal 28, C1428EGA Buenos Aires (Argentina)
In this article we report ionization cross sections of neutral He, Ne, Ar, Kr, and Xe by impact of He{sup +} ions with energies ranging from 25 to 1000 keV/amu. A general theory to deal with dressed projectiles is developed in the context of the Continuum-Distorted-Wave Eikonal-Initial-State approximation. The strategy is based on the use of an effective charge defined in terms of the momentum transfer extracted from the first Born approximation and extensively used in the local plasma approximation to deal with ions in solids. The difference between the actual potential of the projectile and the Coulombic effective one used in the distorted wave functions is treated in first perturbative order. Our results show that the proposed approach gives a very good account of available experiments.
Structural modification of a multiply twinned nanoparticle by ion irradiation: A molecular dynamics study
Jaervi, T. T.; Kuronen, A.; Nordlund, K.; Albe, K. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, FI-00014 Helsinki (Finland); Institut fuer Materialwissenschaft, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany)
We study the possibility of modifying the structure of a multiply twinned nanoparticle by ion irradiation. Molecular dynamics simulations are carried out for the prototypic case of a metastable icosahedral Pt particle bombarded with He and Xe ions in the energy range of 0.1-10 keV. A single xenon impact can be used to melt the particle. It can also induce partial melting, which causes a collapse of the twin boundary structure in the solid part and transformation to single crystalline morphology. Under He irradiation, we observe a saturation of the vacancy concentration, but no untwinning.
Photoionization cross section calculations for the halogen-like ions Kr+ and Xe+
NASA Astrophysics Data System (ADS)
McLaughlin, B. M.; Ballance, C. P.
Photoionization cross section calculations on the halogen-like ions; Kr+ and Xe+ have been performed for a photon energy range from each ion threshold to 15 eV, using large-scale close-coupling calculations within the Dirac-Coulomb R-matrix approximation. The results from our theoretical work are compared with recent measurements made at the ASTRID merged-beam set-up at the University of Aarhus in Denmark and from the Fourier transform ion cyclotron resonance trap method at the SOLEIL synchrotron radiation facility in Saint-Aubin, France Bizau et al (2011 J. Phys. B: At. Mol. Opt. Phys. 44 055205) and the advanced light source Müller (2012 private communication), Aguliar et al (2012 J. Phys.: Conf. Ser. at press). For each of these complex ions our theoretical cross section results over the photon energy range investigated are seen to be in excellent agreement with experiment. Resonance energy positions and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared with experiment for these complex halogen-like ions.
Advanced SiC fiber strain behavior during ion beam irradiation
NASA Astrophysics Data System (ADS)
Jankowiak, A.; Grygiel, C.; Monnet, I.; Serruys, Y.; Colin, C.; Miro, S.; Gelebart, L.; Gosmain, L.; Costantini, J.-M.
The in situ strain behavior upon ion beam irradiation of a Tyranno SA3 SiC fiber was investigated in real time. For this purpose, a tensile test device suitable for micrometrical samples was developed to allow studies in various irradiation facilities. A 7.44 ?m diameter SiC fiber was submitted to both low mechanical loading at 300 MPa and 92-MeV Xe ion beam irradiation at room temperature. The fiber exhibited a gradual increase of its longitudinal strain reaching a maximum value of 0.50% for a total fluence of 5 × 1014 ions cm-2. Raman spectroscopy analyses performed on fibers submitted to the same irradiation conditions have shown significant local structure modification but no evidence of amorphization.
Study on the behavior of oxygen atoms in swift heavy ion irradiated CeO2 by means of synchrotron radiation X-ray
Paris-Sud XI, Université de
1 Study on the behavior of oxygen atoms in swift heavy ion irradiated CeO2 by means of synchrotron Institute of Electric Power Industry, Komae, Tokyo, 201-8511, Japan Keywords:, CeO2, Swift heavy ion on cerium dioxide (CeO2), CeO2 sintered pellets were irradiated with 200 MeV Xe ions at room temperature
Multifragmentation in intermediate energy {sup 129}Xe-induced heavy-ion reactions
Tso, Kin
The {sup 129}Xe-induced reactions on {sup nat}Cu, {sup 89}Y, {sup 165}Ho, and {sup 197}Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the {sup 129}Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.
Oxygen intake in ion irradiated fullerene films
NASA Astrophysics Data System (ADS)
Kumar, Amit; Khan, S. A.; Kumar, Manvendra; Agarwal, D. C.; Singh, Fouran; Tripathi, A.; Govind; Shivaprasad, S. M.; Salomon, J.; Pichon, L.; Pivin, J. C.; Avasthi, D. K.
The present work reports the change in the oxygen content in energetic ion irradiated fullerene films. The oxygen contents in irradiated films have been studied using on-line elastic recoil detection analysis (ERDA) and off-line X-ray photo electron emission (XPS) and nuclear reaction analysis (NRA) techniques. The XPS and NRA techniques show that the oxygen content increases with ion fluence, whereas on-line ERDA measurements reveal that the oxygen content decreases with ion fluence. These experiments give clear evidence that oxygen content in irradiated films increases after exposure to the atmospheric oxygen.
Electronic and geometric structure of Ar+n and Xe+n clusters: The solvation of rare-gas ions by their parent atoms
Hellmut Haberland; Bernd von Issendorff; Thomas Kolar; Hans Kornmeier; Christoph Ludewigt; Andreas Risch
Photoabsorption cross sections for Ar+n, 3<=n<=80, and Xe+n, 3<=n<=30 clusters have been measured. A single absorption maximum in the visible is observed for Ar+n, whose redshift with growing n is interpreted as a delocalization of the charge from a trimer to a tetramer ion. For Xe+3, two maxima, and for Xe+n, n>=5, three maxima are observed. For n>=5 the positive
Heavy Ion Irradiated Ferromagnetic Films: The Cases of Cobalt and Iron
NASA Astrophysics Data System (ADS)
Lieb, K. P.; Zhang, K.; Müller, G. A.; Gupta, R.; Schaaf, P.
Polycrystalline, e-gun deposited Co, Fe and Co/Fe films, tens of nanometers thick, have been irradiated with Ne, Kr, Xe and/or Fe ions to fluences of up to 5 × 1016 ions/cm2. Changes in the magnetic texture induced by the implanted ions have been measured by means of hyperfine methods, such as Magnetic Orientation Mössbauer Spectroscopy (Fe), and by Magneto-Optical Kerr Effect and Vibrating Sample Magnetometry. In Co and CoFe an hcp ? fcc phase transition has been observed under the influence of Xe-ion implantation. For 1016 Xe-ions/cm2, ion beam mixing in the Co/Fe system produces a soft magnetic material with uniaxial anisotropy. The effects have been correlated with changes in the microstructure as determined via X-ray diffraction. The influences of internal and external strain fields, an external magnetic field and pre-magnetization have been studied. A comprehensive understanding of the various effects and underlying physical reasons for the modifications appears to emerge from these investigations.
Patterning magnetic films by ion beam irradiation
B. D. Terris; D. Weller; L. Folks; J. E. E. Baglin; A. J. Kellock; H. Rothuizen; P. Vettiger
We have used ion beam irradiation through a silicon stencil mask to alter the magnetic properties of Co\\/Pt multilayer and FePt chemically-ordered superlattice films. In both systems, ion irradiation disorders the as-grown films which results in a reduction of the magnetic anisotropy. Regularly spaced micrometer-sized regions of magnetically altered material have been produced over areas of a square millimeter. These
Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films
NASA Astrophysics Data System (ADS)
Kimura, Yosuke; Chen, Jinhua; Asano, Masaharu; Maekawa, Yasunari; Katakai, Ryoichi; Yoshida, Masaru
Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe 23+ with fluences of 0, 3 × 10 6, 3 × 10 7, 3 × 10 8 and 3 × 10 9 ions/cm 2, followed by ?-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of 67% isopropanol and 33% water to the ETFE film with an ion-beam irradiation fluence of 3.0 × 10 6 ions/cm 2 was a highly anisotropic proton-conducting material, as the proton conductivity was three or more times higher in the thickness direction than in the surface direction of the membrane.
Ion beam modification of Tl-Ba-Ca-Cu-O type high temperature superconductors during irradiation
Newcomer, P.P.; Morosin, B. [Sandia National Labs., Albuquerque, NM (United States); Wang, L.M. [New Mexico Univ., Albuquerque, NM (United States)
Microstructural modification of high temperature superconductor (HTS) single-crystal plates of Tl-1212 and Tl-2212 (numbers designate the Tl/Ba/Ca/Cu cation ratio) was studied during 1.5 MeV Kr{sup +} and Xe{sup +} ion irradiation with in-situ electron diffraction and after ion irradiation with high resolution TEM (HRTEM). Similar in-situ temperature dependence effects are seen for both phases. During irradiations from 22K to 673K, an amorphous halo develops after very low ion dose or fluence (1.7 {times} 10{sup 12} ions/cm{sup 2}). During irradiation at 100 and 300K, complete amorphization is obtained, while at 22 and {ge}533K, the halo fades slightly and a polycrystalline ring pattern develops, indicating ion irradiation induced crystallization occurred. After a low ion dose (8.5 {times} 10{sup 12} ions/cm{sup 2}) at 100 and 300K, HRTEM reveals amorphous regions 5-20 nm in size which are not columnar and do not all penetrate the entire sample thickness. At 22 and {ge}533K, Moire fringes and misoriented crystallites of cascade size are observed. The 4-6nm crystallites are thallium-rich.
Electron-ion collision rates in noble gas clusters irradiated by femtosecond laser pulse
NASA Astrophysics Data System (ADS)
Dey, R.; Roy, A. C.
We report a theoretical analysis of electron-ion collision rates in xenon gas clusters irradiated by femtosecond laser pulses. The present analysis is based on the eikonal approximation (EA), the first Born approximation (FBA) and the classical (CL) methods. The calculations are performed using the plasma-screened Rogers potential introduced by Moll et al. [J. Phys. B. 43, 135103 (2010)] as well as the Debye potential for a wide range of experimental parameters. We find that the magnitudes of electron-ion collision frequency obtained in the EA do not fall as rapidly with the kinetic energy of electrons as in the FBA and CL methods for higher charge states of xenon ion (Xe8+ and Xe14+). Furthermore, EA shows that the effect of the inner structure of ion is most dominant for the lowest charge state of xenon ion (Xe1+). In the case of the present effective potential, FBA overestimates the CL results for all three different charge states of xenon, whereas for the Debye potential, both the FBA and CL methods predict collision frequencies which are nearly close to each other.
High energy heavy ion irradiation in semiconductors
NASA Astrophysics Data System (ADS)
Srivastava, P. C.; Pandey, S. P.; Sinha, O. P.; Avasthi, D. K.; Asokan, K.
Pd/n-Si and Pd/n-GaAs devices have been irradiated from high energy (˜100 MeV) heavy ions of Au 7+ (gold) and Si 7+ (silicon) to study the irradiation effects in these junction devices on semiconductor substrates. The devices have been characterized from I-V and C-V studies for electronic flow characterization. It has been found that the devices become high resistive on the irradiation and the substrates change the conductivity type from n- to p- on the irradiation of fluence of ˜10 12-10 13 ions/cm 2. The change in conductivity type has been understood as a result of creation of deep acceptors on the irradiation.
Differential electron emission in the ionization of Ne and Xe atoms under fast bare carbon ion impact
NASA Astrophysics Data System (ADS)
Biswas, Shubhadeep; Monti, J. M.; Tachino, C. A.; Rivarola, R. D.; Tribedi, L. C.
Measurement of the energy and angular distributions of the double differential cross section (DDCS) of electron emission from Ne and Xe atoms in collision with 5 MeV u?1 bare carbon ions is reported. This study aimed to investigate the electron emission processes in the case of multi-electronic systems. In general, several clear differences between the electron emission spectra of Ne and Xe are found, which indicate the influence of the increasing number of electrons. For instance, the sharp peak due to the binary nature of collision is almost absent in the case of Xe, unlike Ne, which could be understood due to the increasing contribution from the strongly bound inner shell (such as 4d) electrons for the Xe atom. The forward–backward angular asymmetry has also been derived from the angular distributions. For Xe, the qualitative behaviour of the asymmetry parameter is seen to be quite different since it reveals structures due to Auger contributions. It is, in general, different and much lower than that for Ne, which shows the smooth behaviour that one finds for other lighter atoms like He. The single differential and total cross sections are also derived. The theoretical calculations based on the prior form of the continuum distorted wave-eikonal initial state (CDW-EIS) approximation have been provided for both the targets. Overall, it gives a very good agreement with the energy and the angular distributions of DDCS for Ne. For Xe, the agreement is not as good as for Ne. We also provide a detailed discussion on the DDCS obtained from different sub-shell ionization, estimated in this framework.
Raman spectroscopy of ion irradiated amorphous carbons
NASA Astrophysics Data System (ADS)
Baratta, G. A.; Arena, M. M.; Strazzulla, G.; Colangeli, L.; Mennella, V.; Bussoletti, E.
We have studied, by "in situ" Raman spectroscopy, the modifications induced by 3 keV He + ions on thin amorphous carbon grain deposits. Previous results obtained with our experimental apparatus show that in the case of carbon-containing frozen targets (such as benzene and butane) for doses greater than about 100 eV/mol, ion irradiation induces the formation of an hydrogenated amorphous carbon. In this paper, the bombarded material is already an amorphous carbon with a relatively high order degree. In this case ion irradiation progressively decreases the order degree in the amorphous carbon. This result is in agreement with analogous ion irradiation experiments carried out on highly ordered pyrolitic graphite crystals. These studies are important to understand physical characteristics and evolution of refractory carbon grains in astrophysical environments.
Ion irradiation effects on metallic nanocrystals
Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C.S.; Foran, G.J.; Cookson, D.J.; Byrne, A.P.; Ridgway, M.C. (ASRP); (ANSTO); (ANU)
We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO{sub 2}. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO{sub 2} interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.
Cantilever beam stress measurements during ion irradiation
Sambeek, A.I. Van; Averback, R.S. [Univ. of Illinois, Urbana, IL (United States). Dept. of Materials Science and Engineering
In-situ stress measurements on single crystal MgO and Al{sub 2}O{sub 3} have been performed during ion irradiation. A cantilevered beam sample arrangement was used, with the stress in the implanted layer determined form the deflection of the sample as measured by the change in capacitance between the free end of the sample and a reference electrode. Point defect concentrations are obtained by dividing the volume strain by the defect relaxation volume, with saturation values of 0.8 to 1.2% obtained for 1.0 MeV Ne, Ar and Kr irradiations. Defect production is sublinear with dose, with an efficiency of less than 25% compared to Kinchin-Pease predictions. Ionization induced annealing is evaluated with 1.0 MeV He and 1.0 MeV H irradiations following heavy ion irradiation.
Heavy ion irradiation of crystalline water ice
Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C
Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...
Ion irradiation of preceramic polymer thin films
Pivin, J.C. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay (France); Colombo, P.; Tonidandel, M. [Univ. di Padova (Italy)
Thin films of two preceramic polymers, namely polycarbosilane (PCS) and a silicone resin (SR350), were deposited on Si substrates. Instead of employing conventional annealing at high temperatures in an inert atmosphere, ion irradiation was used to achieve the polymer-to-ceramic conversion. A detailed investigation of the changes in the composition, chemical structure, and hardness was performed by means of ion bean analysis (Rutherford backscattering spectrometry, nuclear reaction analysis, and elastic recoil detection analysis), FTIR, Raman and nanoindentation, respectively. This processing method yielded amorphous Si-C and Si-O-C coatings possessing high hardness and density. Compared to films heat-treated under vacuum at 1,000 C, ion-irradiated ones exhibited a similar hydrogen content, a lower oxygen contamination, and a higher carbon content. Annealing at 1,000 C of previously irradiated films resulted in coatings still possessing a high carbon content and a high hardness.
Heavy Ions Irradiation of Untwinned Single Crystals of YBa_2Cu_3O_7
NASA Astrophysics Data System (ADS)
Petrean, A. M.; Paulius, L. M.; Kwok, W. K.; Dasgupta, D.; Fendrich, J. A.; Crabtree, G. W.; Ronningen, R. M.; Glagola, B.
Vortex pinning is studied in single crystals of YBa_2Cu_3O7 before and after irradiation with heavy ions. The crystals were irradiated with U, Au, or Xe ions. We will present the effects on the critical current density and pinning energies determined from both magnetic hysteresis and electrical transport measurements. We discuss the dose and ion size dependence of the effects. A discussion of these results in terms of the Bose-glass phase will be given. This work was supported by the U.S. DOE, BES-Materials Science contract #W-31-109-ENG-38(AMP, LMP, WKK, DD, GWC, BG), by the NSF-Science and Technology Center for Superconductivity contract #DMR91-20000(JAF) and by the NSF contract #PHY-9528844(RMR) (DD present address: Physics Department, University of Wisconsin, Milwaukee, JAF present address: 313 Microelectronics, 208 N. Wright Street, University of Illinois, Urbana IL, 61801)
Photoionization Cross Section of Xe{sup +} Ion in the Pure 5p{sup 5} {sup 2}P{sub 3/2} Ground Level
Thissen, R. [Laboratoire de Planetologie de Grenoble, UMR 5109 du CNRS, Batiment D de Physique, B.P. 53, 38041 Grenoble (France); Bizau, J. M. [Laboratoire d'Interaction des Rayons X avec la Matiere (LIXAM), UMR 8624 du CNRS, Universite Paris-Sud, Batiment 350, 91405 Orsay cedex (France); Blancard, C. [CEA DAM Ile-de-France, DPTA, Bruyeres-le-Chatel, 91297 Arpajon Cedex (France); Coreno, M. [CNR-IMIP, Rome Branch, c/o GasPhase Beamline, Sincrotrone Trieste, I- 34012 Basovizza, Trieste (Italy); Dehon, C.; Lemaire, J. [Laboratoire de Chimie Physique, UMR 8000 du CNRS, Universite Paris-Sud, Batiment 350, 91405 Orsay cedex (France); Franceschi, P. [Sincrotrone Trieste, SS-14 in Area Science Park, I-34012 Basovizza, Trieste (Italy); Giuliani, A. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, B.P. 48, 91192 Gif-sur-Yvette (France); Cepia, Institut National de la Recherche Agronomique (INRA), B.P. 71627, 44316 Nantes Cedex 3 (France); Nicolas, C. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, B.P. 48, 91192 Gif-sur-Yvette (France)
Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe{sup +} ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe{sup +} with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.
Deformation behavior of ion-irradiated polyimide
NASA Astrophysics Data System (ADS)
Kucheyev, S. O.; Felter, T. E.; Anthamatten, M.; Bradby, J. E.
We study nanoindentation hardness, Young's modulus, and tensile strength of polyimide (Kapton H) films bombarded with MeV light ions in the predominantly electronic stopping power regime. Results show that, for all the ion irradiation conditions studied, bombardment increases the hardness and Young's modulus and decreases the tensile strength. These changes depend close to linearly on ion fluence and superlinearly (with a power-law exponent factor of ˜1.5) on electronic energy loss. Physical mechanisms of radiation-induced changes to mechanical properties of polyimide are discussed.
Effect of swift heavy ion irradiation on single- and multiwalled carbon nanotubes
NASA Astrophysics Data System (ADS)
Olejniczak, Andrzej; Skuratov, Vladimir A.
The effect of irradiation with swift heavy ions on the structure and properties of carbon nanotubes was investigated by Raman spectroscopy. It was found that disordering of the system occurred mainly at the surface. No ordering phenomena have been observed over a whole range of both fluences and electronic stopping powers studied. The disorder parameter (i.e., the ratio of the D and G band intensities (ID/IG)) increases non-linearly with the irradiation dose, showing a tendency to saturate at high fluences. The increase in the disorder parameter upon irradiation was proportional to the square root of the ion fluence. The radiation stability of the few-walled nanotubes was ca. 1.6 higher than that of the single-walled ones. The irradiation with both the Xe and Kr ions leads to essentially the same increase in the ID/IG ratio with respect to the deposited electronic energy density. In the case of the Ar ion irradiation, the observed increase in the ID/IG ratio is much lower, suggesting that the electronic stopping power threshold for defects creation in carbon nanotubes is lower than that for graphite.
Amorphization of crystalline Si due to heavy and light ion irradiation.
Edmondson, P. D.; Riley, D. J.; Birtcher, R. C.; Donnelly, S. E.; Materials Science Division; Univ. of Salford
The formation of amorphous silicon in crystalline silicon by bombardment with light (Si) and heavy (Xe) ions has been investigated by transmission electron microscopy with in situ ion irradiation. Experiments have been carried out at room temperature and low temperature (50 K) and the results are compared to a simple numerical model for amorphization. The results indicate that the amorphization mechanisms for both irradiations are heterogeneous in nature and that numerous overlaps of the collision cascade are generally required to render the crystal amorphous. Following from this, the nature of the material within the confines of collision cascades will be discussed and it will be shown that the individual cascade volume is not necessarily amorphous as previously described in the scientific literature but contains varying degrees of damage depending on the energy deposited within the cascade.
Amorphization of crystalline Si due to heavy and light ion irradiation
Edmondson, P. D.; Riley, D. J.; Donnelly, S. E. [Institute for Materials Research, University of Salford, Manchester M5 4WT (United Kingdom); Birtcher, R. C. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
The formation of amorphous silicon in crystalline silicon by bombardment with light (Si) and heavy (Xe) ions has been investigated by transmission electron microscopy with in situ ion irradiation. Experiments have been carried out at room temperature and low temperature (50 K) and the results are compared to a simple numerical model for amorphization. The results indicate that the amorphization mechanisms for both irradiations are heterogeneous in nature and that numerous overlaps of the collision cascade are generally required to render the crystal amorphous. Following from this, the nature of the material within the confines of collision cascades will be discussed and it will be shown that the individual cascade volume is not necessarily amorphous as previously described in the scientific literature but contains varying degrees of damage depending on the energy deposited within the cascade.
Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation
Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1?×?1014 to 50?×?1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed. PACS code 81.15.Cd; 78.66.Jg; 61.80.Jh PMID:24717078
Swelling in reactor-conditioned nickel-ion irradiated nimonic PE16. [Neutron irradiation and nickel-ion irradiation
Bajaj, R.; Diamond, S.; Chickering, R.W.; Bleiberg, M.L.
Nimonic PE16 solution treated and aged and neutron irradiated at three temperatures to a fluence up to 5.9 X 10/sup 22/ n/cm/sup 2/ was bombarded to an additional nominal nickel ion dose of 150 displacements per atom (dpa) at various temperatures. The swelling determined by transmission electron microscopy is described and comparisons are made with results obtained from ion bombardments of virgin material and high-fluence neutron irradiated material.
Measured and calculated SF-6 collision and swarm ion transport data in SF6 -Ar and SF6 -Xe mixtures.
Benhenni, M; de Urquijo, J; Yousfi, M; Hernandez-Avila, J L; Merbahi, N; Hinojosa, G; Eichwald, O
The measurement of the mobility of SF-6 in the mixtures SF6 -Ar and SF6 -Xe is reported over the density-reduced electric field strength E/N 1-180 Td (1 Townsend = 10(-17) V cm(2)), from a time-resolved pulsed Townsend technique. Simultaneously, the mobility of SF-6 in the same binary mixtures has been calculated from a set of collision cross sections for SF-6 -Ar, SF-6 -Xe, and SF-6 - SF6 using a Monte Carlo simulation procedure for ion transport. The good agreement between measured and calculated mobilities in these gas mixtures has led us to conclude that the validation of our cross section sets is confirmed. The elastic collision cross section, a predominant process for ion energies lower than about 10 eV, was determined from a semiclassical JWKB approximation using a rigid core potential model for the ion-neutral systems under consideration. This elastic cross section was then added to several other inelastic collision cross sections found in the literature for ion conversion, electron detachment of SF-6 and charge transfer. Moreover, the calculations of the mobility and the ratios of the transverse and longitudinal diffusion coefficients to the mobility were extended into a much wider E/N range from 1 to 4000 Td. Additionally, we have also calculated the energy distribution functions and the reaction coefficients for ion conversion and electron detachment. Finally, we have shown that the range of validity for the calculation of the mobility in gas mixtures from Blanc's law is only valid for the low E/N region, where the interaction is dominated by elastic collisions and the ion distribution function remains essentially Maxwellian. PMID:15903586
Anisotropic deformation of metallo-dielectric core shell colloids under MeV ion irradiation
NASA Astrophysics Data System (ADS)
Penninkhof, J. J.; van Dillen, T.; Roorda, S.; Graf, C.; van Blaaderen, A.; Vredenberg, A. M.; Polman, A.
We have studied the deformation of metallo-dielectric core-shell colloids under 4 MeV Xe, 6 and 16 MeV Au, 30 MeV Si and 30 MeV Cu ion irradiation. Colloids of silica surrounded by a gold shell, with a typical diameter of 400 nm, show anisotropic plastic deformation under MeV ion irradiation, with the metal flowing conform the anisotropically deforming silica core. The 20 nm thick metal shell imposes a mechanical constraint on the deforming silica core, reducing the net deformation strain rate compared to that of pure silica. In colloids consisting of a Au core and a silica shell, the silica expands perpendicular to the ion beam, while the metal core shows a large elongation along the ion beam direction, provided the silica shell is thick enough (>40 nm). A minimum electronic energy loss of 3.3 keV/nm is required for shape transformation of the metal core. Silver cores embedded in a silica shell show no elongation, but rather disintegrate. Also in planar SiO 2 films, Au and Ag colloids show entirely different behavior under MeV irradiation. We conclude that the deformation model of core-shell colloids must include ion-induced particle disintegration in combination with thermodynamical effects, possibly in combination with mechanical effects driven by stresses around the ion tracks.
Chromosomal instability induced by heavy ion irradiation
NASA Technical Reports Server (NTRS)
Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Morgan, W. F.
PURPOSE: To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint. MATERIALS AND METHODS: Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes. RESULTS: Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively. CONCLUSIONS: Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.
Phase formation in ion-irradiated and annealed Ni-rich Ni-Al thin films
Alexander, D.E.; Was, G.S. (Department of Nuclear Engineering, University of Michigan, Ann Arbor, Michigan 48109 (US)); Rehn, L.E. (Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (USA))
Phase formation was studied in ion-irradiated multilayer and coevaporated Ni-20 at. % Al films supported by Cu, Mo, and Ni transmission electron microscopy (TEM) grids. Irradiation with either 700-keV Xe or 1.7-MeV Xe, to doses sufficient to homogenize the multilayers ({ge}7.5{times}10{sup 15} cm{sup {minus}2}), resulted in the formation of metastable supersaturated {gamma} and HCP phases in both film types. Post-irradiation annealing of multilayers at 450 {degree}C for 1 h transformed the metastable phases to a two-phase {gamma}+{gamma}{prime} microstructure. In the absence of Cu, the formation of {gamma}{prime} appeared to proceed by a traditional diffusional growth mechanism, resulting in small ({lt}50 A) {gamma}{prime} precipitates in {gamma} matrix grains. The presence of Cu caused the formation of a dual-phase {gamma}+{gamma}{prime} structure (i.e., distinct, equal-sized grains of {gamma} and {gamma}{prime}) during post-irradiation annealing. It is suggested that copper affected the nucleation of {gamma}{prime} precipitates and increased the kinetics of growth resulting in the dual-phase morphology. Strong irradiation-induced textures were observed in the multilayers that were less pronounced in the coevaporated films. The texture in the multilayers was attributed to the presence of a slight as-evaporated texture combined with the enhanced atomic mobility due to the heat-of-mixing released during irradiation. The irradiation-induced texture appeared to be necessary for the formation of the dual-phase structure since it likely provided high-diffusivity paths for Cu to diffuse into the film from the TEM grid.
Ion irradiated graphite exposed to fusion-relevant deuterium plasma
NASA Astrophysics Data System (ADS)
Deslandes, Alec; Guenette, Mathew C.; Corr, Cormac S.; Karatchevtseva, Inna; Thomsen, Lars; Ionescu, Mihail; Lumpkin, Gregory R.; Riley, Daniel P.
Graphite samples were irradiated with 5 MeV carbon ions to simulate the damage caused by collision cascades from neutron irradiation in a fusion environment. The ion irradiated graphite samples were then exposed to a deuterium plasma in the linear plasma device, MAGPIE, for a total ion fluence of ?1 × 1024 ions m-2. Raman and near edge X-ray absorption fine structure (NEXAFS) spectroscopy were used to characterize modifications to the graphitic structure. Ion irradiation was observed to decrease the graphitic content and induce disorder in the graphite. Subsequent plasma exposure decreased the graphitic content further. Structural and surface chemistry changes were observed to be greatest for the sample irradiated with the greatest fluence of MeV ions. D retention was measured using elastic recoil detection analysis and showed that ion irradiation increased the amount of retained deuterium in graphite by a factor of four.
Phase transformations in ion-irradiated silicides
NASA Technical Reports Server (NTRS)
Hewett, C. A.; Lau, S. S.; Suni, I.; Hung, L. S.
The present investigation has three objectives. The first is concerned with the phase transformation of CoSi2 under ion implantation and the subsequent crystallization characteristics during annealing, taking into account epitaxial and nonepitaxial recrystallization behavior. The second objective is related to a study of the general trend of implantation-induced damage and crystallization behavior for a number of commonly used silicides. The last objective involves a comparison of the recrystallization behavior of cosputtered refractory silicides with that of the ion-implanted silicides. It was found that epitaxial regrowth of ion-irradiated CoSi2 occurred for samples with an epitaxial seed left at the Si/CoSi2 interface. A structural investigation of CoSi2 involving transmission electron microscopy (TEM) showed that after high-dose implantation CoSi2 is amorphous.
Effects of swift heavy ions irradiation parameters on optical properties of muscovite mica
Zhang, Sheng-Xia; Zeng, Jian; Song, Yin; Mo, Dan; Yao, Hui-Jun; Duan, Jing-Lai; Sun, You-Mei; Hou, Ming-Dong
Muscovite mica sheets with a thickness of 25 {\\mu}m were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL. The fluences ranged from 1$\\times$10^{10} ions/cm^2 to 8$\\times$10^{11} ions/cm^2. The electronic energy loss (dE/dx)_e was increased from 14.7 keV/nm to 31.2 keV/nm. The band gap and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet- visible spectroscopy. Periodic fringes in long wave length of the absorption spectra caused by interference phenomenon, were disturbed as the (dE/dx)_e increased. It was suggested that the chemical bonds between Tetrahedral-Octohedral-Tetrahedral (TOT) layers of mica were destroyed. Thus the smooth surface was cleaved after irradiation. The band gap was narrowed down with the increasing (dE/dx)_e and fluences. The values of Urbach energy were increased as the (dE/dx)_e and fluences gradually increased. It was indicated that the amount of defects and the proportion of amorphous structure were increased in mica irradiated under...
Formation of a metastable crystalline phase during ion irradiation of spinel
Devanathan, R.; Yu, Ning; Sickafus, K.; Nastasi, M.
We have examined the radiation resistance of magnesio-aluminate spinel by irradiating single crystals of MgAl{sub 2}O{sub 4} with 400 keV Xe++ions at 100 K. At low irradiation doses, the material transformed into a metastable crystalline phase with half the lattice spacing of the original crystal. Electron diffraction analysis revealed that this structural change can be explained in terms of the redistribution of cations among octahedral, tetrahedral, and three- fold coordinated interstitial sites of the close-packed anion lattice. Corresponding to this transformation, the hardness and elastic modulus increased with dose to values about 10% greater than those of unirradiated spinel. We believe that the formation of this metastable phase plays an important role in determining the radiation resistance of spinel.
Graphitization of polymer surfaces by low-energy ion irradiation
Lazareva, I.; Koval, Y.; Alam, M.; Stroemsdoerfer, S.; Mueller, P. [Physikalisches Institut III, Universitaet Erlangen-Nuernberg, Erwin-Rommel Strasse 1, 91058 Erlangen (Germany)
The surface of several polymers was graphitized by low-energy ion irradiation. Their conducting properties were studied as a function of the energy of the ions and the irradiation temperature. It was found that at rather modest ion energies ({approx}1000 eV) and irradiation temperatures (<400 deg. C), polymer surfaces transform to a graphitized state. The graphitized layer consists of overlapping graphite islands with a diameter of 1-3 nm and exhibits a semimetallic conductivity. Gradually reducing the energy of the ions and the irradiation temperature, the authors observed a transition from semimetallic to variable range hopping conductivity.
Neurite outgrowth on fluorinated polyimide film micropatterned by ion irradiation
NASA Astrophysics Data System (ADS)
Okuyama, Y.; Sato, M.; Nagaoka, S.; Kawakami, H.; Suzuki, Y.; Iwaki, M.
In this study, we investigated neurite outgrowth on a fluorinated polyimide film micropatterned by ion irradiation. We used the fluorinated polyimide because of its excellent thermal and mechanical properties and biocompatibility. Rattus norvegicus chromaphin (PC12) cells were used for in vitro studies. The polyimide films were irradiated with He +, Ne + or Kr + at 1 × 10 14 ions/cm 2 using an ion-beam mask. The lines in the mask were 120 and 160 ?m wide and 120-160 ?m apart. PC12 cells were selectively adhered on the polyimide film micropatterned by Kr +-irradiation. However, the neurite length on the film irradiated by Kr + was shorter than that determined in the film irradiated by He +. On the other hand, neurite outgrowth on the polyimide film micropatterned by He +-irradiation was at least 100 ?m in length. This initial study indicated the enhanced outgrowth of PC12 cells on the fluorinated polyimide film micropatterned by ion irradiation.
Dependence of cross sections for multi-electron loss by 6 mev/amu xe18+ ions on target atomic number
Peng, Yong
for multi-electron loss on target atomic number by using 6 MeV/amu Xe18+ ions and to compare the results with the n-body Classical Trajectory Monte Carlo calculations. A secondary objective of this project is to determine the extent to which the cross...
Chemical reactivity and ion beam irradiation behaviour of perovskite- and zirconolite-nuclear ceramics type
NASA Astrophysics Data System (ADS)
Larguem, H.; Trocellier, P.; Tarrida, M.; Madon, M.; Poissonnet, S.; Gosset, D.; Leseigneur, O.; Martin, H.; Bonnaillie, P.; Beck, L.; Vaubaillon, S.; Miro, S.
Oxide ceramics of two neighboring families: perovskite A(II)B(IV)O3 and zirconolite A(II)B(IV)C(IV)2O7 have been synthesized by a classical solid route. Substitution of divalent cation (Ca) by trivalent cation (Nd) was tested on zirconolite compositions. Then, the ceramic pellets were submitted to aqueous leaching tests at 90 °C in deionized water. Some of them were previously ion irradiated with 150 keV Xe+ within a fluence range 5 × 1013-1 × 1015 cm-2 in order to study the effect of ion damaging on their intrinsic chemical reactivity. X-ray diffraction (XRD), electron microprobe analysis (EMA), scanning electron microscopy (SEM) and ion beam analysis (IBA) methods were used to characterize the evolution of the crystallinity level and the surface chemical composition of the ceramics after each step (synthesis, irradiation, leaching). The alteration mechanism of unirradiated titanate ceramics appears to be not uniform at the sample surface. Chemical durability of zirconolite is shown to be dependent both on the pH of the aqueous solution and the ceramic composition. Surface hydration only concerns a very thin layer, typically 200 nm and the hydrogen content does not go beyond 1-2 at.%. No differences have been detected in the leaching behaviour of unirradiated or irradiated perovskite samples.
Graphitization of polymer surfaces by scanning ion irradiation
NASA Astrophysics Data System (ADS)
Koval, Yuri
Graphitization of polymer surfaces was performed by low-energy Ar+ and He+ ion irradiation. A method of scanning irradiation was implemented. It was found that by scanning ion irradiation, a significantly higher electrical conductivity in the graphitized layers can be achieved in comparison with a conventional broad-beam irradiation. The enhancement of the conductance becomes more pronounced for narrower and better collimated ion beams. In order to analyze these results in more detail, the temperature dependence of conductance of the irradiated samples was investigated. The results of measurements are discussed in terms of weak localization corrections to conductance in disordered metals. The observed effects can be explained by enlargement of graphitic patches, which was achieved with the scanning ion irradiation method.
Heavy ion irradiation induces autophagy in irradiated C2C12 myoblasts and their bystander cells.
Hino, Mizuki; Hamada, Nobuyuki; Tajika, Yuki; Funayama, Tomoo; Morimura, Yoshihiro; Sakashita, Tetsuya; Yokota, Yuichiro; Fukamoto, Kana; Mutou, Yasuko; Kobayashi, Yasuhiko; Yorifuji, Hiroshi
Autophagy is one of the major processes involved in the degradation of intracellular materials. Here, we examined the potential impact of heavy ion irradiation on the induction of autophagy in irradiated C2C12 mouse myoblasts and their non-targeted bystander cells. In irradiated cells, ultrastructural analysis revealed the accumulation of autophagic structures at various stages of autophagy (i.e. phagophores, autophagosomes and autolysosomes) within 20 min after irradiation. Multivesicular bodies (MVBs) and autolysosomes containing MVBs (amphisomes) were also observed. Heavy ion irradiation increased the staining of microtubule-associated protein 1 light chain 3 and LysoTracker Red (LTR). Such enhanced staining was suppressed by an autophagy inhibitor 3-methyladenine. In addition to irradiated cells, bystander cells were also positive with LTR staining. Altogether, these results suggest that heavy ion irradiation induces autophagy not only in irradiated myoblasts but also in their bystander cells. PMID:20685830
Optical birefringence of Zn nanoparticles embedded in silica induced by swift heavy-ion irradiation.
Amekura, H; Okubo, N; Ishikawa, N
Zn nanoparticles (NPs) embedded in a silica matrix subjected to irradiation with swift heavy ions of 200 MeV Xe¹?? have been found to undergo shape elongation from spheres to prolate-spheroids while maintaining the major axes of the NPs in parallel alignment. The directionally-aligned Zn spheroids enable acquisition of optical properties, such as linear dichroism and birefringence. In this paper, the birefringence of the Zn spheroids was evaluated by the crossed-Nicols (XN) transmittance, where a sample was inserted between a pair of optical polarizers that were set in an orthogonal configuration. Linearly-polarized light aligned by the first polarizer was transformed to an elliptic polarization by the birefringence of the Zn spheroids. The existence of the birefringence was confirmed by the non-zero transmittance of the second polarizer in the orthogonal configuration. The sample irradiated with a fluence of 5.0 × 10¹³ ions/cm² exhibited a maximum XN transmittance of 2.1% at a photon energy of ~4 eV. The XN transmission was observed down to a fluence of 1.0 × 10¹² ions/cm², but reduced below the detection limit at a fluence of 1.0 × 10¹¹ ions/cm². The possible application of the elongated Zn NPs as a polarizer with nanometric thickness working in the near- and mid-ultraviolet region is discussed. PMID:25606918
Emulation of reactor irradiation damage using ion beams
G. S. Was; Z. Jiao; E. Beckett; A. M. Monterrosa; O. Anderoglu; B. H. Sencer; M. Hackett
The continued operation of existing light water nuclear reactors and the development of advanced nuclear reactor depend heavily on understanding how damage by radiation to levels degrades materials that serve as the structural components in reactor cores. The first high dose ion irradiation experiments on a ferritic-martensitic steel showing that ion irradiation closely emulates the full radiation damage microstructure created in-reactor are described. Ferritic-martensitic alloy HT9 (heat 84425) in the form of a hexagonal fuel bundle duct (ACO-3) accumulated 155 dpa at an average temperature of 443°C in the Fast Flux Test Facility (FFTF). Using invariance theory as a guide, irradiation of the same heat was conducted using self-ions (Fe++) at 5 MeV at a temperature of 460°C and to a dose of 188 displacements per atom. The void swelling was nearly identical between the two irradiations and the size and density of precipitates and loops following ion irradiation are within a factor of two of those for neutron irradiation. The level of agreement across all of the principal microstructure changes between ion and reactor irradiations establishes the capability of tailoring ion irradiations to emulate the reactor-irradiated microstructure.
Defect production in ion-irradiated aluminum
NASA Astrophysics Data System (ADS)
Averback, R. S.; Benedek, R.; Merkle, K. L.; Sprinkle, J.; Thompson, L. J.
Residual-resistivity measurements on ion-irradiated thin films are used to study defect production in aluminum. The energy and mass dependences of damage rates indicate that defect production efficiency (relative to the modified Kinchin-Pease relation) strongly decreases at recoil energies between 5 and 10 keV. At high energy the efficiency approaches an asymptotic value of 0.5. These results are similar to those observed in copper and silver. Binary-collision simulations were performed for copper, silver and aluminum to investigate the relationship of cascade structure to defect production efficiency. The mechanism primarily responsible for the reduced defect production efficiency in cascades in aluminum is thought to be the subthreshold recombination of Frenkel pairs during the thermal-spike phase of the cascade.
Dissolution of ordered precipitates under ion irradiation
Camus, E.; Bourdeau, F.; Abromeit, C.; Wanderka, N.; Wollenberger, H. [Hahn-Meitner-Institut Berlin GmbH (Germany)
The stability of the ordered {gamma}{prime} precipitates under 300-keV Ni{sup +} irradiation was investigated between room temperature and 623 K. The two competing mechanisms of destabilization by cascade producing irradiation, i.e. disordering and dissolution of the {gamma}{prime} precipitates in Nimonic PE16 alloy, has been studied separately by electron microscopy and field-ion microscopy with atom probe. At high temperatures, the precipitates are stable. At intermediate temperatures, the precipitates dissolve by ballistic mixing into the matrix, but the interface is restored by the radiation-enhanced atomic jumps. The order in the precipitates remains stable. At low temperatures, the precipitates are dissolved by atomic mixing. The dissolution proceeds in a diffusional manner with a diffusion coefficient normalized by the displacement rate D/K = 0.75 nm{sup 2}dpa{sup {minus}1}. The precipitates become disordered by a fluence of 0.1 dpa, whereas precipitate dissolution needs much higher fluences.
Electron-emission processes in highly charged Ar and Xe ions impinging on highly ordered pyrolytic graphite at energies just above the kinetic threshold
NASA Astrophysics Data System (ADS)
Bodewits, E.; Hoekstra, R.; Dobes, K.; Aumayr, F.
At keV energies, many electronic processes contribute to the emission of secondary electrons in the interaction of highly charged ions on surfaces. To unravel contributions resulting from isolated hollow atoms in front of the surface or embedded in the electron gas of the target, heavy highly charged Ar and Xe ions are collided on highly ordered pyrolytic graphite (HOPG). A light target material as HOPG assures straight-line trajectories in the subsurface range. By a systematic change of incidence angle and energy of low-charged Ar and Xe ions, the kinetic electron emission component is determined. Separating out the kinetic energy contribution for the highly charged ions yields pure potential-energy-driven secondary-electron yields. From these yields it is concluded that in contrast to metallic targets, only a small fraction of the secondary electrons stem from above the surface. The lack of above-surface emission is likely due to the semimetallic electronic structure of HOPG. The subsurface emission is found to scale with the increase in binding energy of the inner-shell hole when incrementing the charge state of the projectile Ar or Xe ions.
Longitudinal dilation behavior of ion-irradiated Tyranno™-SA SiC fibers at elevated-temperatures
NASA Astrophysics Data System (ADS)
Shimoda, Kazuya; Colin, Christian
Advanced SiC fibers with low oxygen content, nearly-stoichiometric composition and high crystallinity, are envisaged as reinforcement in SiCf/SiC composites for next generation nuclear reactors. In this study, we performed ion-irradiation experiments at GANIL (Caen, France) on the advanced fiber, Tyranno™-SA grade-3, with 95 MeV Xe ions at room-temperature. To prevent the damage gradient in fiber, the fibers were irradiated on two sides with two fluence levels (2.46 × 1014 ions/cm2 for the first side +2.52 × 1014 ions/cm2 for the opposite side and 9.89 × 1014 ions/cm2 for the first side +1.02 × 1015 ions/cm2 for the opposite side). According to TRIM-code calculation, the ion irradiation damages in the fibers affected the entire volume of the fibers, with estimations of 0.05 and 0.2 dpa. The structural evolution under the ion irradiation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. The results did not reveal a complete amorphization. The gradual transition in physical properties, such as deformation and coefficient of thermal expansion (CTE) and electrical conductivity, during heating and cooling up to 1800 °C were monitored by longitudinal dilation test of a single fiber. These physical property changes (or recoveries) of the ion-irradiated fibers were categorized in the following temperature regions (1st stage: <200 °C (no recovering), 2nd stage: 200-1400 °C (recovering) and 3rd stage: >1400 °C (almost completely recovered)). In particular, a linear recovery in the medium range of 800-1400 °C during heating had very limited property changes.
Nonuniversality due to inhomogeneous stress in semiconductor surface nanopatterning by low-energy ion-beam irradiation
NASA Astrophysics Data System (ADS)
Moreno-Barrado, A.; Castro, M.; Gago, R.; Vázquez, L.; Muñoz-García, J.; Redondo-Cubero, A.; Galiana, B.; Ballesteros, C.; Cuerno, R.
A lack of universality with respect to ion species has been recently established in nanostructuring of semiconductor surfaces by low-energy ion-beam bombardment. This variability affects basic properties of the pattern formation process, like the critical incidence angle for pattern formation, and has remained unaccounted for. Here, we show that nonuniform generation of stress across the damaged amorphous layer induced by the irradiation is a key factor behind the range of experimental observations, as the form of the stress field is controlled by the ion/target combination. This effect acts in synergy with the nontrivial evolution of the amorphous-crystalline interface. We reach these conclusions by contrasting a multiscale theoretical approach, which combines molecular dynamics and a continuum viscous flow model, with experiments using Xe+and Ar+ ions on a Si(100) target. Our general approach can apply to a variety of semiconductor systems and conditions.
Ion energy distributions, electron temperatures, and electron densities in Ar, Kr, and Xe pulsed discharges
Economou, Demetre J.
of plasma induced Si recess on device performance degradation.9 Wang and Wendt10 and Agarwal and Kush- ner11 one material versus the other. For example, atomic layer etching of Si may be achieved with an ion, the inductively coupled plasma reactor was equipped with a Faraday shield to block capacitive coupling
Swift heavy ion irradiation of crystalline CdTe
NASA Astrophysics Data System (ADS)
Steinbach, T.; Bierschenk, Th; Milz, S.; Ridgway, M. C.; Wesch, W.
The influence of high electronic energy deposition in cadmium telluride (CdTe) was investigated using Rutherford backscattering spectrometry in channelling configuration as well as high-resolution transmission electron microscopy. Swift heavy ion irradiation was performed at room temperature with 185 MeV Au ions at perpendicular and non-perpendicular ion incidence. Independent of the ion incidence angle, neither ion beam induced point defects nor amorphous ion tracks were observed along the ion path. In contrast, the irradiated layer possesses a high crystalline quality even after irradiation with high ion fluences, i.e. multiple ion overlap. Nevertheless, irradiation with swift heavy ions leads to the formation of extended defects in a thin layer close to the sample surface. With increasing ion fluence the concentration of these extended defects increases continuously. This suggests that high electronic energy deposition causes the formation of defects, however, the combination of the high defect mobility within the thermal spike and the high ionicity of CdTe may benefit an effective recovery of the ionic bonds and consequently an easy recovery of the lattice, i.e. a nearly perfect recrystallization. The experimentally observed high defect resistivity enables a high doping of foreign atoms in CdTe over a wide depth range without the formation of lattice defects which is important for the use of CdTe as an effective absorber for solar cells.
Endommagement produit dans des films de fer ? irradies a 77 K par different ions
NASA Astrophysics Data System (ADS)
Jaouen, C.; Riviere, J. P.; Fayoux, C.; Dinhut, J. F.; Delafond, J.
Radiation damage in pure Fe is studied at 77 K during bombardment with ions of increasing energy and atomic mass, i.e. B, Ar, Fe, Xe. The film thickness and the beam energy are selected such that a central damaged layer of comparable relative width for the different incident ions is produced in the samples. The electrical resistivity variations of the specimens are continuously measured as a function of the ion fluence and interpreted in terms of defect production in displacement cascades. The experimental number of stable Frenkel pairs produced per incident ion is determined from the initial damage rates ??0 and compared with the calculated values based on a modified Kinchin-Pease model. It is found that the damage efficiency decreases as a function of the incident ion mass or deposited energy per atom. These results are compared on the one hand with similar studies done in f.c.c. metals (Au, Cu and Ag) and on the other hand with damage rate studies for other types of irradiation in pure Fe.
Strong hyperfine induced quenching of a metastable state in Xe{sup {bold +}} observed by hyperfine selective laser probing of a stored ion beam
Mannervik, S.; Brostroem, L.; Lidberg, J.; Norlin, L.; Royen, P. [Atomic Physics, Stockholm University, Frescativaegen 24, S-104 05 Stockholm (Sweden)] [Atomic Physics, Stockholm University, Frescativaegen 24, S-104 05 Stockholm (Sweden); [Physics Department in Frescati, Royal Institute of Technology, Frescativaegen 24, S-104 05 Stockholm (Sweden); [Physics Department, Stockholm University, Vanadisvaegen 9, S-113 46 Stockholm (Sweden)
A hyperfine state selective laser probing technique is presented to be used for lifetime determination of metastable states in an ion storage ring. Evidence for a drastic difference between the decay rates of the hyperfine states of the metastable level 5{ital d}{sup 4}{ital D}{sub 7/2} in {sup 129}Xe{sup +} has been obtained by this method. {copyright} {ital 1996 The American Physical Society.}
The joining of graphene sheets under Ar ion beam irradiation.
Wu, Xin; Zhao, Haiyan; Murakawa, Hidekazu
In this paper, Ar ion beam irradiation was proposed as a method to join the overlapped graphene sheets and the joining process was researched by classical molecular dynamics simulation. The results showed that the ion irradiation behavior could successfully induce the joining of overlapped graphene sheets. The joining results were found to be attributed to the saturation of dangling bonds generated during irradiation. Meanwhile, it was confirmed that the ion parameters had influence on the properties of the joint and the optimum ion parameters were obtained using tensile test simulation. The optimum ion dose and ion energy were 1.9 x 10(15) ions/cm2 and 60 eV, respectively. To emphasize the importance of the irradiation, we further studied the joining possibilities of graphene sheets when the irradiation was replaced by a large force (160 nN) acting on the upper sheet and we demonstrated that the joining results wouldn't happen without the irradiation. At last, the influence of the chirality of the graphene sheets on the joining process were discussed, and it was found that graphene sheets with the same chirality had higher matching-degree, which would result in better joint. PMID:25935991
Effect of ion irradiation on tribological properties of composite coatings
NASA Astrophysics Data System (ADS)
Platonova, E. S.; Guchenko, S. A.; Syzdykova, A. Sh; Laurinas, V. Ch; Yurov, V. M.; Lysenko, E. N.; Mylnikova, T. S.
The paper discusses the results of the research in the effect of ion irradiation on tribological properties of multiphase ion-plasma coatings. It is shown that all the investigated coatings behave differently under ion irradiation: the Zn-Al, Fe-Al, Zn-Cu-Al coating is radiation-resistant and the friction coefficient does not virtually change; the Cr-Mn-Si-Cu-Fe- Al coating exhibits twofold increase in the friction coefficient, and that for Mn-Fe-Cu-Al coating decreases threefold. These changes are related to changes which occur in the coating surface under ion bombardment.
Ion irradiation testing of Improved Accident Tolerant Cladding Materials
Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tesmer, Joseph R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
This report summarizes the results of ion irradiations conducted on two FeCrAl alloys (named as ORNL A&B) for improving the accident tolerance of LWR nuclear fuel cladding. After irradiation with 1.5 MeV protons to ~0.5 to ~1 dpa and 300°C nanoindentations were performed on the cross-sections along the ion range. An increase in hardness was observed in both alloys. Microstructural analysis shows radiation induced defects.
Ion irradiation effects on frozen methanol (CH_3OH)
M. E. Palumbo; A. C. Castorina; G. Strazzulla
We present some experimental results on the chemical-physical effects induced by ion irradiation on frozen methanol (CH_3OH), pure and mixed with water (H_2O). We have studied, by ``in situ'' infrared (IR) spectroscopy, samples of solid CH_3OH and H_2O:CH_3OH mixtures before and after irradiation, with 3-30 keV ions, at low pressures and low temperature (10 K). We have derived the integrated
The interactions of high-energy, highly charged Xe ions with buckyballs
Ali, R.; Berry, H.G.; Cheng, S. [and others
Ionization and fragmentation have been measured for C{sub 60} molecules bombarded by highly charged (up to 35+) xenon ions with energies ranging up to 625 MeV. The observed mass distribution of positively charged fragments is explained in terms of a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. Preliminary results of measurements on VUV photons emitted in these interactions are also presented.
Effect of swift heavy ion irradiations in polycrystalline aluminum nitride
J. C. Nappé; M. Benabdesselam; Ph. Grosseau; B. Guilhot
Thanks to its high thermal conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However, its behavior under irradiation is not entirely well understood. In order to catch a glimpse of this behavior, specimens were irradiated with swift heavy ions of different energies then characterized by both thermally stimulated luminescence and optical absorption
Heavy-ion irradiation induced diamond formation in carbonaceous materials.
Daulton, T. L.
The basic mechanisms of metastable phase formation produced under highly non-equilibrium thermodynamic conditions within high-energy particle tracks are investigated. In particular, the possible formation of diamond by heavy-ion irradiation of graphite at ambient temperature is examined. This work was motivated, in part, by earlier studies which discovered nanometer-grain polycrystalline diamond aggregates of submicron-size in uranium-rich carbonaceous mineral assemblages of Precambrian age. It was proposed that the radioactive decay of uranium formed diamond in the fission particle tracks produced in the carbonaceous minerals. To test the hypothesis that nanodiamonds can form by ion irradiation, fine-grain polycrystalline graphite sheets were irradiated with 400 MeV Kr ions. The ion irradiated graphite (and unirradiated graphite control) were then subjected to acid dissolution treatments to remove the graphite and isolate any diamonds that were produced. The acid residues were then characterized by analytical and high-resolution transmission electron microscopy. The acid residues of the ion-irradiated graphite were found to contain ppm concentrations of nanodiamonds, suggesting that ion irradiation of bulk graphite at ambient temperature can produce diamond.
The effects of swift heavy-ion irradiation on helium-ion-implanted silicon
NASA Astrophysics Data System (ADS)
Li, B. S.; Du, Y. Y.; Wang, Z. G.; Shen, T. L.; Li, Y. F.; Yao, C. F.; Sun, J. R.; Cui, M. H.; Wei, K. F.; Zhang, H. P.; Shen, Y. B.; Zhu, Y. B.; Pang, L. L.
Cross-sectional transmission electron microscopy (XTEM) was used to study the effects of irradiation with swift heavy ions on helium-implanted silicon. <1 0 0>-oriented silicon wafers were implanted with 30 keV helium to a dose of 3 × 1016 He+/cm2 at 600 K. Subsequently, the helium-implanted Si wafers were irradiated with 792 MeV argon ions. The He bubbles and extended defects in the wafers were examined via XTEM analysis. The results reveal that the mean diameter of the He bubbles increases upon Ar-ion irradiation, while the number density of the He bubbles decreases. The microstructure of the He bubbles observed after Ar-ion irradiation is comparable to that observed after annealing at 1073 K for 30 min. Similarly, the mean size of the extended defects, i.e., Frank loops, increases after Ar-ion irradiation. Possible mechanisms are discussed.
Inner-shell photoionization and core-hole decay of Xe and XeF2.
Southworth, Stephen H; Wehlitz, Ralf; Picón, Antonio; Lehmann, C Stefan; Cheng, Lan; Stanton, John F
Photoionization cross sections and partial ion yields of Xe and XeF2 from Xe 3d5/2, Xe 3d3/2, and F 1s subshells in the 660-740 eV range are compared to explore effects of the F ligands. The Xe 3d-?f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF2 cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Comparisons of the ion products from the atom and molecule following Xe 3d photoionization show that the charge-state distribution of Xe ions is shifted to lower charge states in the molecule along with production of energetic F(+) and F(2+) ions. This suggests that, in decay of a Xe 3d core hole, charge is redistributed to the F ligands and the system dissociates due to Coulomb repulsion. The ion products from excitation of the F 1s-LUMO resonance are different and show strong increases in the yields of Xe(+) and F(+) ions. The subshell ionization thresholds, the LUMO resonance energies, and their oscillator strengths are calculated by relativistic coupled-cluster methods and agree well with measurements. PMID:26071705
Inner-shell photoionization and core-hole decay of Xe and XeF2
NASA Astrophysics Data System (ADS)
Southworth, Stephen H.; Wehlitz, Ralf; Picón, Antonio; Lehmann, C. Stefan; Cheng, Lan; Stanton, John F.
Photoionization cross sections and partial ion yields of Xe and XeF2 from Xe 3d5/2, Xe 3d3/2, and F 1s subshells in the 660-740 eV range are compared to explore effects of the F ligands. The Xe 3d-?f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF2 cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Comparisons of the ion products from the atom and molecule following Xe 3d photoionization show that the charge-state distribution of Xe ions is shifted to lower charge states in the molecule along with production of energetic F+ and F2+ ions. This suggests that, in decay of a Xe 3d core hole, charge is redistributed to the F ligands and the system dissociates due to Coulomb repulsion. The ion products from excitation of the F 1s-LUMO resonance are different and show strong increases in the yields of Xe+ and F+ ions. The subshell ionization thresholds, the LUMO resonance energies, and their oscillator strengths are calculated by relativistic coupled-cluster methods and agree well with measurements.
Study of the zirconium oxidation under heavy ion irradiation
N. Bérerd; N. Moncoffre; A. Chevarier; H. Jaffrézic; H. Faust; E. Balanzat
The objective of the present paper is to put in evidence the influence of damages due to the collision cascades which take place at the end of the heavy ion micrometer range, on the zirconium surface oxidation.A comparison between two zirconium oxidation experiments under heavy ion irradiation performed in the same temperature and pressure conditions is presented. In the first
Precipitation of copper in iron under swift ion irradiations
NASA Astrophysics Data System (ADS)
Barbu, A.; Pareige, P.; Jacquet, V.
After irradiation was carried out on the Fe1.34 at% Cu supersaturated solution with 2.5 MeV electrons and 188 MeV oxygen ions at 290°C, we report new results about copper precipitation under 5.07 GeV krypton irradiation. The precipitation observed on line by electrical resistivity and after irradiation by tomographic atom probe experiments and microhardness measurements, shows that the kinetics of copper precipitation (in term of dpa calculated using the modified Kinchin-Pease model) is hundred times larger with GeV krypton ions than with MeV electrons and is the same under oxygen and electron irradiations. We show that such a behaviour can be explained only by assuming that the energy deposited in electronic excitations along the path of swift ions is actually able to induce precipitation in metallic supersaturated solid solutions.
Ion and neutral energy flux distributions to the cathode in glow discharges in Ar/Ne and Xe/Ne mixtures
NASA Astrophysics Data System (ADS)
Capdeville, H.; Pédoussat, C.; Pitchford, L. C.
The work presented in the article is a study of the heavy particle (ion and neutral) energy flux distributions to the cathode in conditions typical of discharges used for luminous signs for advertising ("neon" signs). The purpose of this work is to evaluate the effect of the gas mixture on the sputtering of the cathode. We have combined two models for this study: a hybrid model of the electrical properties of the cathode region of a glow discharge and a Monte Carlo simulation of the heavy particle trajectories. Using known sputtering yields for Ne, Ar, and Xe on iron cathodes, we estimate the sputtered atom flux for mixtures of Ar/Ne and Xe/Ne as a function of the percent neon in the mixture.
Edge-on ion irradiation of electron microscope specimens
Otero, M.P. (Argonne National Lab., IL (United States) Fundacao de Tecnologia Industrial (FTI), Lorena, SP (Brazil)); Allen, C.W. (Argonne National Lab., IL (United States))
A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.
Edge-on ion irradiation of electron microscope specimens
Otero, M.P. [Argonne National Lab., IL (United States)]|[Fundacao de Tecnologia Industrial (FTI), Lorena, SP (Brazil); Allen, C.W. [Argonne National Lab., IL (United States)
A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.
Inhomogeneous microstructural evolution in ion-irradiated austenitic steel
NASA Astrophysics Data System (ADS)
Sekimura, N.; Taguchi, M.; Ishino, S.
Thin foils of Ti-modified austenitic steel (JPCA) are irradiated with heavy ions to investigate characteristic microstructural evolution up to heavy irradiation dose at medium temperature. Ordered arrays of small loops with spacing of about 40 nm are observed in about half of grains with foil edge in the specimen irradiated to 1.0 dpa. This structure is found to be very stable for further irradiation. Elastic interaction of the loops formed in a thin foil is considered to limit the cluster density. Crystallographic orientation of defect arrays is considered to be enhanced to minimize elastic interaction energy between defects clusters.
PuXe, UXe, UPb chronology and isotope systematics of ancient zircons from Western Australia
PuXe, UXe, UPb chronology and isotope systematics of ancient zircons from Western Australia of short-lived 244 Pu has been confirmed in a suite of 16 Hadean detrital zircons from Western Australia irradiated the zircons with thermal neutrons to generate Xe from 235 U neutron fission. 131 Xe/134 Xe and 132
Formation of nanosized hills on Ti 3SiC 2 oxide layer irradiated with swift heavy ions
NASA Astrophysics Data System (ADS)
Nappé, J. C.; Monnet, I.; Audubert, F.; Grosseau, Ph.; Beauvy, M.; Benabdesselam, M.
The Ti 3SiC 2 refractory compound that combines properties of both metals and ceramics is a fuel cladding candidate under investigation for Gas-cooled Fast Reactor. Its behavior under swift heavy ion irradiation (Xe ions, 92 MeV, 10 19 m -2) was investigated. Significant and unexpected surface changes have been highlighted: hills have been observed by AFM on the surface of Ti 3SiC 2. Such a topographic modification has never been observed in other materials irradiated in similar conditions. The characterization of these hills by both XPS and X-TEM has highlighted that the surface modifications do not appear in Ti 3SiC 2 but in the amorphous oxide layer located on the sample surface before irradiation. Moreover, the thickness of this oxide layer grew under irradiation dose. The comparison with previous irradiations has led to the conclusion that this surface modification stems from electronic interactions in this amorphous layer, and that there is a threshold in the electronic stopping power to overcome to form hills.
Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires
Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar+ ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio. PMID:25951108
Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires.
Johannes, Andreas; Noack, Stefan; Wesch, Werner; Glaser, Markus; Lugstein, Alois; Ronning, Carsten
Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar(+) ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio. PMID:25951108
Optical properties of silver clusters formed by ion irradiation
J. C. Pivin; M. A. García; H. Hofmeister; A. Martucci; M. Sendova Vassileva; M. Nikolaeva; O. Kaitasov; J. Llopis
: Precipitation of silver clusters in silica is achieved by different methods: ion implantation, ion beam mixing of superimposed\\u000a layers and ion irradiation of films deposited by means of co-sputtering or sol-gel technique. Main features of the nanoparticles\\u000a depending on the preparation method are investigated by TEM. The optical extinction resonance of these clusters is analysed\\u000a in terms of sizes
University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis
NASA Astrophysics Data System (ADS)
Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Dickerson, C.; Gerczak, T. J.; Field, C. R.; Kriewaldt, K.; Sridharan, K.; Allen, T. R.
The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to ˜200 ?A and ˜5 ?A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.
The influence of helium ion irradiation on amorphous hydrocarbon films
NASA Astrophysics Data System (ADS)
Fan, Hongyu; Sun, Li; Yang, Deming; Niu, Jinhai; Guo, Liping; Yang, Qi; Bi, Zhenhua; Liu, Dongping
Amorphous hydrocarbon films were irradiated with 60-140 keV He ions at the dose ranging from 1.0 × 1015 to 1.0 × 1017 ions/cm2. The films about 1.4 ?m thick were deposited on Si substrates and irradiated at room temperature. The surface and mechanical properties of as-deposited and He ion irradiated hydrocarbon films were analyzed by using atomic force microscopy (AFM), AFM-based nanoindentation and scratching tests. Their chemical compositions and structural properties were evaluated by FTIR and Raman measurements. Analysis showed that the He ion irradiation led to a decrease in their surface roughness and an increase in the nanohardness and scratching resistance. FTIR measurements indicated that the content of bonded H atoms in hydrocarbon samples was greatly decreased due to the He ion irradiation, and a dense and covalent three-dimensional network was formed in films. The Raman data confirmed the microstructural evolution of samples into a dense metastable structure containing a large fraction of sp2 C clusters.
Forsterite Amorphisation by Ion Irradiation: Monitoring by Infrared Spectroscopy
J. R. Brucato; G. Strazzulla; G. Baratta; L. Colangeli
We present experimental results on crystal--amorphous transition of forsterite (Mg2SiO4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been sythesised in laboratory and irradiated with low energy (30--60 keV) ion beams. Structural changes during irradiation with H+, He+, C+, and Ar++ have been observed and monitored by infrared spectroscopy. The fraction of crystalline forsterite converted into amorphous is a function of the energy deposited by nuclear collision by ions in the target. Laboratory results indicate that ion irradiation is a mechanism potentially active in space for the amorphisation of silicates. Physical properties obtained in this work can be used to model the evolution of silicate grains during their life cycle from evolved stars, through different interstellar environments and up to be incorporated in Solar System objects.
Folding two dimensional crystals by swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Ochedowski, Oliver; Bukowska, Hanna; Freire Soler, Victor M.; Brökers, Lara; Ban-d'Etat, Brigitte; Lebius, Henning; Schleberger, Marika
Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS2 and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS2 does not.
Absolute photoionization cross sections for Xe4+, Xe5+, Xe6+ near13.5 nm: Experiment and Theory
Aguilar, A.; Gillaspy, J.D.; Gribakin, G.F.; Phaneuf, R.A.; Gharaibeh, M.F.; Kozlov, M.G.; Bozek, J.D.; Kilcoyne, A.L.D.
Absolute photoionization cross-section measurements for amixture of ground and metastable states of Xe4+, Xe5+, and Xe6+ arereported in the photon energy range of 4d->nf transitions, which occurwithin or adjacent to the 13.5 nm window for extreme ultravioletlithography light source development. The reported values allow thequantification of opacity effects in xenon plasmas due to these 4d nfautoionizing states. The oscillator strengths for the 4d->4f and4d->5f transitions in Xeq+ (q=1-6) ions are calculated usingnonrelativistic Hartree-Fock and random phase approximations. These arecompared with published experimental values for Xe+ to Xe3+ and with thevalues obtained from the present experimental cross-section measurementsfor Xe4+ to Xe6+. The calculations assisted in the determination of themetastable content in the ion beams for Xe5+ and Xe6+. The experimentswere performed by merging a synchrotron photon beam generated by anundulator beamline of the Advanced Light Source with an ion beam producedby an electron cyclotron resonance ion source.
A laser spectroscopic study on Xe{sup +} ion transport phenomena in the ExB discharge of a Hall effect thruster
Mazouffre, S.; Gawron, D.; Kulaev, V. [ICARE, CNRS, 1c Avenue de la Recherche Scientifique, 45071 Orleans (France); Luna, J. Perez [LAPLACE, 118 Route de Narbonne, 31062 Toulouse (France); Sadeghi, N. [LSP, Joseph-Fourier University-CNRS, 140 Avenue de la Physique, BP87, 38402 St Martin d'Heres (France)
The Velocity Distribution Function (VDF) of metastable Xe{sup +} ions was measured along the channel axis of the 5 kW-class PPS registered X000 Hall effect thruster by means of Laser Induced Fluorescence spectroscopy at 834.72 nm for various voltages, magnetic fields and mass flow rates. Axial velocity and dispersion profiles are compared to on-axis profiles obtained with the 1.5 kW-class PPS100 thruster. Outcomes of the comparison are threefold. (i) The broadening of the FDV across the region of strong magnetic field is a general feature for Hall thrusters. It originates in the overlap between ionization and acceleration layers. The velocity dispersion increases with the discharge voltage; it reaches up to 200 eV in unit of kinetic energy at 700 V. (ii) Most of the acceleration potential ({approx_equal}70%) is localized outside the thruster channel whatever the thruster size and operating conditions. The electric field moves upstream when the applied voltage is ramped up; in other words the fraction of potential inside the channel increases with the voltage; (iii) A non negligible amount of very slow and very fast (kinetic energy higher than the applied potential) Xe{sup +} ions are always observed. Such ions may find their origin in space and temporal oscillations of the electric field as suggested by numerical simulations carried out with a hybrid model.
Visible Laser Action of Dy3+ Ions in Monoclinic KY(WO4)2 and KGd(WO4)2 Crystals under Xe-Flashlamp Pumping
Alexander Kaminskii; Uwe Hömmerich; Doyle Temple; Ken-ichi Ueda; Sergey Bagayev; Aleksey Pavlyulk
Pulsed laser action in the novel visible laser channels 4F9\\/2--> ^6H13\\/2 (at ≈0.57 mum) and 4F9\\/2-->^6H11\\/2 (at ≈0.66 mum) of Dy3+ ions in monoclinic KY(WO4)2 and KGd(WO4)2 single crystals at nitrogen cryogenic temperature under Xe-flashlamp pumping is excited for the first time. All observed lasing emissions are identified. Some spectroscopic characteristics of the investigated crystals are also presented.
Scaling law of single ion–atom impact ionization cross sections of noble gases from He to Xe at strong perturbative energies
NASA Astrophysics Data System (ADS)
Ren, Ping-Yuan; Zou, Xian-Rong; Shao, Jian-Xiong; Wang, Shi-Yao; Zhou, Man; Zhou, Wang; Yang, Ai-Xiang; Yan, Peng-Xun; Chen, Xi-Meng
We extend our previous work of a classical over-barrier ionization (COBI) model to calculate the single ionization cross sections of noble gases ranging from He to Xe at strong perturbative energies. The calculation results are in good agreement with extensive experimental data. The scaling law of single ion–atom impact ionization cross sections of noble gases on projectile charge q and energy E, also on target ionization energy I is drawn from the model. Project supported by the National Natural Science Foundation of China (Grants Nos. 11174116, and 11175075).
Raman spectrum study of graphite irradiated by swift heavy ions
NASA Astrophysics Data System (ADS)
Zhai, Peng-Fei; Liu, Jie; Zeng, Jian; Yao, Hui-Jun; Duan, Jing-Lai; Hou, Ming-Dong; Sun, You-Mei; Ewing, Rodney Charles
Highly oriented pyrolytic graphites are irradiated with 40.5-MeV and 67.7-MeV 112Sn-ions in a wide range of fluences: 1 × 1011 ions/cm2?1 × 1014 ions/cm2. Raman spectra in the region between 1200 cm?1 and 3500 cm?1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-MeV Sn-ions than that observed for 67.7-MeV Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ~ 3-cm?1 frequency shift toward lower wavenumber for the D band and ~ 6-cm?1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1 × 1014 ions/cm2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover, the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.
Enhanced biocompatibility of PDMS (polydimethylsiloxane) polymer films by ion irradiation
NASA Astrophysics Data System (ADS)
Ionescu, M.; Winton, B.; Wexler, D.; Siegele, R.; Deslantes, A.; Stelcer, E.; Atanacio, A.; Cohen, D. D.
PDMS films several microns thick deposited on polished Si wafers were irradiated with Mg, Ta, and Fe in the low energy range of 40 keV to 200 keV, and for doses of 10 16-10 18 ions/cm 2. After irradiation the films surface is self-organised into 3D coherent and semi-coherent domains. As a consequence of the surface irradiation conditions and the surface boundary conditions, some domains are highly ordered in the form of parallel waves of approximately 1 ?m in height, or the result can be semi-ordered regions or disordered regions. In addition, the surface energy of the irradiated polymer is increasing, as reflected in the decrease in its surface hydrophobicity, which is beneficial for cell adhesion. The irradiated samples were tested in vivo, and the results show an increase in viable cell count of up to 650%.
Irradiation-induced hardening mechanism of ion irradiated JLF-1 to high fluences
H. Ogiwara; A. Kohyama; H. Tanigawa; H. Sakasegawa
Reduced-activation ferritic\\/martensitic steels, RAFs, are leading candidates for blanket and first wall of fusion reactors, and effects of displacement damage and helium production on mechanical properties and microstructures are important subjects. The objective of this work is to clarify radiation hardening mechanism by means of ion irradiation and nano indentation. JLF-1 (9Cr–2W–V, Ta) steel was irradiated to 60dpa at 693,
Tungsten ions produced by infrared pulsed laser irradiation
NASA Astrophysics Data System (ADS)
Torrisi, L.
Energetic ions have been obtained irradiating a tungsten target with a Q-switched Nd:Yag laser, 1064 nm wavelength, 9 ns pulse width, 900 mJ maximum pulse energy and power density of the order of 10(10) W/cm(2) . The laser-target interaction induces a strong metal etching with production of plasma in front of the target. The plasma contains neutrals and ions with high charge state. Time-of-flight measurements are presented for qualitative analysis of the ion production. A cylindrical electrostatic ion analyzer permits measuring of the yield of emitted ions, the charge state of detected ions and the ion energy distribution. Measurements indicate that, at a laser fluence of the order of 100 J/cm(2) , the charge state may reach 9+ and the ion energy reaches about 5 keV. The ion energy distribution is given as a function of the charge state. Experimental results indicate that an electrical field is developed along the normal to the plane of the target surface, which accelerates the ions up to high velocity. The ion velocity distributions follow a "shifted Maxwellian distribution", which the author has corrected for the Coulomb interactions occurring inside the plasma.
Angular Dependence of SOI Transistor Response to Heavy Ion Irradiation
Mélanie Raine; Marc Gaillardin; Philippe Paillet; Jean-Etienne Sauvestre; Olivier Duhamel; Arnaud Bournel
Experimental results showing angular dependence for charge collection in SOI transistors under heavy ion irradiation are presented. Geant4 and Synopsys Sentaurus simulations are performed to analyze these results in terms of direct ionization effects. The influence of the beam direction in relation to that of the transistor's channel on the transistor's response is underlined. Depending on the considered beam direction,
Magnetization and susceptibility of ion irradiated granular magnetite films
Jiang, Weilin; McCloy, John S.; Lea, Alan S.; Sundararajan, J. A.; Yao, Qi; Qiang, Y.
Superparamagnetic granular magnetite (Fe3O4) films with an average grain size of 3 nm have been found to be magnetized following 5.5 MeV Si2+ ion irradiation to a fluence of 1.0E16 ions/cm2 near room temperature. The film underwent a phase transition to ferromagnetism after the irradiation. X-ray diffraction study shows that the average grain size increased to 23 nm. There is a dramatic change in the microstructure, featuring particle aggregation and material condensation. Magnetic domains in the irradiated film are observed in the size range of tens to several hundreds of nanometers. The change in the magnetic properties is attributed to irradiation induced grain growth and structural modifications that lead to occurrence of magnetic anisotropy. There are dipolar interactions between the nanoparticles in both the unirradiated and irradiated films. Data fits for the in-phase alternating current magnetic susceptibility of the unirradiated film indicate that the blocking temperature is ~150 K, depending on frequency. A gradual Verwey transition for the irradiated film occurs at ~75 K, above which the susceptibility exhibits unusual behavior: a linear decrease with decreasing temperature. There are irreversible processes of magnetic domains during cooling and warming up between 10 and 300 K.
Effects of Ga ion-beam irradiation on monolayer graphene
Wang, Quan; Mao, Wei; Zhang, Yanmin; Shao, Ying; Ren, Naifei [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)] [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Ge, Daohan [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China) [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China)
The effects of Ga ion on the single layer graphene (SLG) have been studied by Raman spectroscopy (RS), SEM, and field-effect characterization. Under vacuum conditions, Ga ion-irradiation can induce disorders and cause red shift of 2D band of RS, rather than lattice damage in high quality SLG. The compressive strain induced by Ga ion decreases the crystalline size in SLG, which is responsible for the variation of Raman scattering and electrical properties. Nonlinear out-put characteristic and resistance increased are also found in the I-V measurement. The results have important implications during CVD graphene characterization and related device fabrication.
Precipitation of semiconducting carbon nanoparticles in ion irradiated gels
NASA Astrophysics Data System (ADS)
Kumar, Amit; Singh, F.; Khan, S. A.; Agarwal, D. C.; Tripathi, A.; Avasthi, D. K.; Pivin, J. C.
Sol-gel materials are converted into glassy ceramics when subjected to ion irradiation or heat treatments. In addition, a demixing occurs in the obtained glasses when their structure is metastable. In the present work, we have irradiated silicon-based gels with 120 MeV and 2 GeV Au ions at different fluences from 8 × 10 9 to 2 × 10 13 ions/cm 2. Ion irradiation leads to formation of carbon nanoclusters, which have semiconducting properties. Photoluminescence and optical absorption spectroscopies are used to identify the semiconducting properties of carbon clusters. High resolution transmission electron microscopy (HRTEM) and energy filtered imaging of C atoms show that C particles with a size of ˜4 nm are produced and they are aligned along ion tracks. Elastic recoil detection analysis has been performed to determine the kinetics of the H evolution and to evaluate the track radius, which matches with the radius obtained from HRTEM. The obtained aligned carbon clusters (wires) would find useful applications as field emitters or nanocontacts.
Ion emission from fused silica under 157-nm irradiation
NASA Astrophysics Data System (ADS)
John, Sharon R.; Leraas, J. A.; Langford, S. C.; Dickinson, J. T.
We present a summary of initial work on the etching of silica at 157 nm. At fluences well below the threshold for plasma formation, we have characterized the direct desorption of atomic ions from fused silica surfaces during 157-nm irradiation. The ion identities and kinetic energies were determined by time-resolved mass spectroscopy. The principal ions are Si+ and O+. The emission intensities are dramatically increased by treatments that are expected to increase the density of surfaces defects. Molecular dynamics simulations of the silica surface suggest that silicon ions bound at surface oxygen vacancies (analogous to E' centers) provide suitable configurations for emission. We propose that emission is best understood in terms of a hybrid mechanism involving both antibonding chemical forces (Menzel-Gomer-Redhead model) and repulsive electrostatic forces on the adsorbed ion after laser excitation of the underlying defect.
In-situ high temperature irradiation setup for temperature dependent structural studies of materials under swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Kulriya, P. K.; Kumari, Renu; Kumar, Rajesh; Grover, V.; Shukla, R.; Tyagi, A. K.; Avasthi, D. K.
An in-situ high temperature (1000 K) setup is designed and installed in the materials science beam line of superconducting linear accelerator at the Inter-University Accelerator Centre (IUAC) for temperature dependent ion irradiation studies on the materials exposed with swift heavy ion (SHI) irradiation. The Gd2Ti2O7 pyrochlore is irradiated using 120 MeV Au ion at 1000 K using the high temperature irradiation facility and characterized by ex-situ X-ray diffraction (XRD). Another set of Gd2Ti2O7 samples are irradiated with the same ion beam parameter at 300 K and simultaneously characterized using in-situ XRD available in same beam line. The XRD studies along with the Raman spectroscopic investigations reveal that the structural modification induced by the ion irradiation is strongly dependent on the temperature of the sample. The Gd2Ti2O7 is readily amorphized at an ion fluence 6 × 1012 ions/cm2 on irradiation at 300 K, whereas it is transformed to a radiation-resistant anion-deficient fluorite structure on high temperature irradiation, that amorphized at ion fluence higher than 1 × 1013 ions/cm2. The temperature dependent ion irradiation studies showed that the ion fluence required to cause amorphization at 1000 K irradiation is significantly higher than that required at room temperature irradiation. In addition to testing the efficiency of the in-situ high temperature irradiation facility, the present study establishes that the radiation stability of the pyrochlore is enhanced at higher temperatures.
Ion beam irradiated optical channel waveguides
NASA Astrophysics Data System (ADS)
Bányász, I.; Rajta, I.; Nagy, G. U. L.; Zolnai, Z.; Havranek, V.; Pelli, S.; Veres, M.; Himics, L.; Berneschi, S.; Nunzi-Conti, G.; Righini, G. C.
Nowadays, in the modern optical communications systems, channel waveguides represent the core of many active and passive integrated devices, such as amplifiers, lasers, couplers and splitters. Different materials and fabrication processes were investigated in order to achieve the aforementioned optoelectronic circuits with low costs and high performance and reproducibility. Nevertheless, the 2D guiding structures fabrication continues to be a challenging task in some of optical materials due to their susceptibility to mechanical and/or chemical damages which can occur during the different steps of the fabrication process. Here we report on channel waveguides demonstration in erbium doped Tungsten - Tellurite (Er3+:TeO2-WO3) glasses and BGO crystals by means of a masked ion beam and/or direct writing processes performed at different energy MeV and ions species. The evidence of the waveguides formation was investigated by microscopy techniques and micro Raman spectroscopy.
Effect of irradiation spectrum on the microstructure of ion-irradiated Al{sub 2}O{sub 3}
Zinkle, S.J. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
Polycrystalline samples of alpha-alumina have been irradiated with various ions ranging from 3.6 MeV Fe{sup +} to 1 MeV H{sup +} ions at 650 C. Cross-section transmission electron microscopy was used to investigate the depth-dependent microstructure of the irradiated specimens. The microstructure following irradiation was observed to be dependent on the irradiation spectrum. In particular, defect cluster nucleation was effectively suppressed in specimens irradiated with light ions such as 1 MeV H{sup +} ions. On the other hand, light ion irradiation tended to accelerate the growth rate of dislocation loops. The microstructural observations are discussed in terms of ionization enhanced diffusion processes.
Time-of-Flight Measurements of Ion and Electron from Xenon Clusters Irradiated with a Soft X-Ray Laser Pulse
S. Namba; N. Hasegawa; M. Nishikino; M. Kishimoto; T. Kawachi; M. Tanaka; Y. Ochi; K. Nagashima; K. Takiyama
The photoionization process in xenon clusters irradiated with a soft x-ray laser pulse (h?=89.2 eV, intensity: ~1010 W\\/cm2) was examined using a time-of-flight mass spectrometer, where the laser photon energy was high enough to ionize Xe 4d inner\\u000a electrons (threshold: 67.55 eV for 4d5\\/2 and 69.54 eV for 4d3\\/2). The dominant ion yield resulting from Auger decay of 4d hole
Enhancement of Secondary Hydrocarbon Ion Emission Yield from Graphite Irradiated with Energetic Carbon Cluster Ion Beams
NASA Astrophysics Data System (ADS)
Shibata, Hiromi; Saitoh, Yuichi; Chiba, Atsuya; Narumi, Kazumasa
When radiations, such as UV lights, X-rays, gamma-rays, and energetic electrons and ions, irradiate interstellar grains, excitation and ionization of the atoms and molecules around the surface of the grains occur, and chemical reactions are induced. Thus many kinds of organic and inorganic molecules are produced on the interstellar grains. We have observed the yield enhancement of secondary hydrocarbon cluster ion emission from graphite irradiated by energetic cluster ions. As energetic cluster ions can bombard a very small (atomic size) area of a solid surface with many atoms simultaneously and release large kinetic energy in a very short time (from femto-to pico-second region), nonlinear effects or synergetic effects are caused. This effect enhances the secondary ion emission yields. Energetic cluster ion beams used for the study of secondary ion emission processes were pro-duced by the TIARA tandem accelerator at Takasaki Advanced Radiation Research Institute, JAEA. A time of flight (TOF) mass spectrometer combined with a pulsed cluster ion beam was used for a secondary ion measurement. In this report we present some results of positive and negative secondary ion emission from a highly oriented pyrolytic graphite (HOPG) target bombarded with 0.5 MeV/atom (˜ 42 keV/amu) C1+ ˜ C8+ ions. The total secondary ion yields except for yields of hydrogen ions (H+, H2+, H3+ or H-) from a HOPG target bombarded with carbon cluster ions are presented. The yields of negative secondary ions for all incident cluster ions Cn+ are about twice of positive ion yields and the super-linear relation can be seen. We will discuss about this enhancement of the yield of secondary emission.
Kr Ion Irradiation Study of the Depleted-Uranium Alloys
J. Gan; D. Keiser; B. Miller; M. Kirk; J. Rest; T. Allen; D. Wachs
Fuel development for the Reduced Enrichment Research and Test Reactor program is tasked with the development of new low-enriched uranium nuclear fuels that can be employed to replace existing highly enriched uranium fuels currently used in some research reactors throughout the world. For dispersion-type fuels, radiation stability of the fuel/cladding interaction product has a strong impact on fuel performance. Three depleted uranium alloys are cast for the radiation stability studies of the fuel/cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Si, Al)3, (U, Mo)(Si, Al)3, UMo2Al20, U6Mo4Al43, and UAl4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200ºC to ion doses up to 2.5 × 1015 ions/cm2 (~ 10 dpa) with an Kr ion flux of 1012 ions/cm2-sec (~ 4.0 × 10-3 dpa/sec). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.
Kr ion irradiation study of the depleted-uranium alloys.
Gan, J.; Keiser, D. D.; Miller, B. D.; Kirk, M. A.; Rest, J.; Allen, T. R.; Wachs, D. M. (Materials Science Division); (INL); (Univ. of Wisconsin)
Fuel development for the reduced enrichment research and test reactor (RERTR) program is tasked with the development of new low enrichment uranium nuclear fuels that can be employed to replace existing high enrichment uranium fuels currently used in some research reactors throughout the world. For dispersion type fuels, radiation stability of the fuel-cladding interaction product has a strong impact on fuel performance. Three depleted-uranium alloys are cast for the radiation stability studies of the fuel-cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Al, Si){sub 3}, (U, Mo)(Al, Si){sub 3}, UMo{sub 2}Al{sub 20}, U{sub 6}Mo{sub 4}Al{sub 43} and UAl{sub 4}. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200 C to ion doses up to 2.5 x 10{sup 19} ions/m{sup 2} ({approx}10 dpa) with an Kr ion flux of 10{sup 16} ions/m{sup 2}/s ({approx}4.0 x 10{sup -3} dpa/s). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.
Late degeneration in rabbit tissues after irradiation by heavy ions
NASA Technical Reports Server (NTRS)
Lett, J. T.; Cox, A. B.; Keng, P. C.; Lee, A. C.; Su, C. M.; Bergtold, D. S.
Results are presented for investigations of the late effects of heavy-ion irradiation on rabbit tissues which were undertaken to assess the hazards associated with the long-term exposure of humans to heavy ions in space during such activities as the construction of solar power stations or voyages to Mars. White rabbits approximately six weeks old were exposed to various doses of collimated beams of 400-MeV/n Ne ions, 570 MeV/n Ar ions and Co-60 gamma rays directed through both eyes, and the responses of the various tissues (hair follicles, skin, cornea, lens, retina, Harderian glands, bone and forebrain) were examined. Proliferating tissues are found to exhibit high damage levels in the early and late periods following irradiation, while terminally differentiating tissues repond to radiation most intensely in the late period, years after irradiation, with no intermediate recovery. The results obtained from rabbits are used to predict the occurrence of late tissue degeneration in the central nervous system, terminally differentiating systems and stem cells of humans one or more decades following exposure to radiation levels anticipated during long-duration space flights. The studies also indicate that tissues may be prematurely aged in the sense that tissue life spans may be shortened without the development of malignancies.
An infrared study of pure and ion irradiated frozen formamide
NASA Astrophysics Data System (ADS)
Brucato, J. R.; Baratta, G. A.; Strazzulla, G.
Context.The chemical evolution of formamide (HCONH2), a molecule of astrobiological interest that has been tentatively identified in interstellar ices and in cometary coma, has been studied in laboratory under simulated astrophysical conditions such as ion irradiation at low temperature.Aims.To evaluate the abundances of formamide observed in space or in laboratory, the integrated absorbances for all the principal IR features of frozen amorphous pure formamide deposited at 20 K were measured. Further evidence that energetic processing of ices occurring in space is extremely relevant both to astrochemistry and to astrobiology has been found, showing that new molecular species are synthesized by ion irradiation at a low temperature.Methods.Pure formamide were deposited at 20 K and IR transmission spectra measured for different ice thicknesses. The ice thickness was derived by looking at the interference pattern (intensity versus time) of a He-Ne laser beam reflected at an angle of 45 deg by the vacuum-film and film-substrate interfaces. Samples of formamide ice were irradiated with 200 keV H+ ions and IR spectra recorded at different ion fluences.Results.New molecules were synthesized among which are CO, CO2, N2O, isocyanic acid (HNCO), and ammonium cyanate (NH4^+OCN^-). Some of these species remain stable after warming up to room temperature.
STM and Raman spectroscopic study of graphite irradiated by heavy ions
Gao, Hongjun
; Heavy ions; Scanning tunnel microscopy; Raman spectroscopy 1. Introduction When a swift heavy ion on the presentation of new Raman scattering results on ion irradiation because it is sensitive to structural disorderSTM and Raman spectroscopic study of graphite irradiated by heavy ions J. Liu a,*, M.D. Hou a , C
Slowing down of fast electrons as probe for charging and decharging dynamics of ion-irradiated insulators
NASA Astrophysics Data System (ADS)
de Filippo, E.; Lanzanó, G.; Amorini, F.; Geraci, E.; Grassi, L.; La Guidara, E.; Lombardo, I.; Politi, G.; Rizzo, F.; Russotto, P.; Volant, C.; Hagmann, S.; Rothard, H.
The slowing down of fast electrons emitted from insulators [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Kr, Ag, Xe; 20-64 MeV/u) was measured by the time-of-flight method at LNS, Catania and GANIL, Caen. The charge buildup, deduced from both convoy- and binary-encounter electron peak shifts, leads to target material-dependent potentials (6.0 kV for Mylar, 2.8 kV for PP). The number of projectiles needed for charging up (charging-up time constant) is inversely proportional to the electronic energy loss. After a certain time, a sudden decharging occurs. For low beam currents, charging-up time, energy shift corresponding to maximum charge buildup, and time of decharging are regular. For high beam currents, the time intervals become irregular (chaotic).
Magnetic properties of graphite irradiated with MeV ions
Ramos, M. A.; Munoz-Martin, A.; Climent-Font, A. [CMAM and Instituto de Ciencia de Materiales 'Nicolas Cabrera', Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Barzola-Quiquia, J.; Esquinazi, P. [Division of Superconductivity and Magnetism, Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig (Germany); Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)
We have studied the change in the magnetic properties produced on highly oriented pyrolytic graphite samples by irradiation of H, C, and N ions in the mega-electron-volt energy range. The use of specially made sample holders for the magnetic measurements provided high reproducibility allowing us to obtain directly the irradiation effects without any corrections or subtractions. Our results show that three magnetic phenomena are triggered by the defects produced by the irradiation, namely, Curie-type paramagnetism, ferromagnetism and an anomalous paramagnetic state that appears as precursor of the magnetic ordered state. Using SRIM simulations to estimate the amount of vacancies produced by the irradiation, the Curie-type paramagnetic response indicates an effective Bohr magneton number per nominally produced vacancy p=0.27+-0.02mu{sub B}. Direct measurements of the surface sample temperature during irradiation and the decrease in the (as-received) paramagnetic as well as ferromagnetic contributions after irradiation indicate that self-heating is one of the causes for small yield of ferromagnetism. Taking into account the hydrogen distribution in the virgin samples, the obtained results indicate that the induced ferromagnetism appears when the average vacancy distance is {approx}2 nm in the near surface region.
Magnetization and susceptibility of ion-irradiated granular magnetite films
Jiang, W.; McCloy, J. S.; Lea, A. S.; Sundararajan, J. A.; Yao, Q.; Qiang, Y. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Physics Department, University of Idaho, Moscow, Idaho 83844 (United States)
Porous granular films of magnetite (Fe{sub 3}O{sub 4}) with grains of {approx}3 nm in size were prepared using a state-of-the-art nanocluster deposition system. The films are initially superparamagnetic but become magnetized following Si{sup 2+} ion irradiation. A significant increase in the grain size and a dramatic change in the microstructure are observed. There are dipolar interactions between the nanoparticles in both the unirradiated and irradiated films. The in-phase alternating current magnetic susceptibility of the unirradiated film shows a blocking temperature of {approx}150 K, depending on frequency. A broadened Verwey transition for the irradiated film occurs at {approx}75 K, above which the susceptibility exhibits unusual behavior: a nearly linear decrease with decreasing temperature. There are irreversible domain rotations in the irradiated film during zero-field cooling and warming cycles between 10 and 300 K. The observed behavior of the irradiated granular films is quite distinct from that of metallic nanostructures after irradiation, and is due to the dramatic change in microstructures.
Metastable hydronium ions in UV-irradiated ice
Moon, Eui-Seong; Kang, Heon [Department of Chemistry, Seoul National University, 1 Gwanak-ro, Seoul 151-747 (Korea, Republic of)
We show that the irradiation of UV light (10-11 eV) onto an ice film produces metastable hydronium (H{sub 3}O{sup +}) ions in the ice at low temperatures (53-140 K). Evidence of the presence of metastable hydronium ions was obtained by experiments involving adsorption of methylamine onto UV-irradiated ice films and hydrogen-deuterium (H/D) isotopic exchange reaction. The methylamine adsorption experiments showed that photogenerated H{sub 3}O{sup +} species transferred a proton to the methylamine arriving at the ice surface, thus producing the methyl ammonium ion, which was detected by low energy sputtering method. The H{sub 3}O{sup +} species induced the H/D exchange of water, which was monitored through the detection of water isotopomers on the surface by using the Cs{sup +} reactive ion scattering method. Thermal and temporal stabilities of H{sub 3}O{sup +} and its proton migration activity were examined. The lifetime of the hydronium ions in the amorphized ice was greater than 1 h at {approx}53 K and decreased to {approx}5 min at 140 K. Interestingly, a small portion of hydronium ions survived for an extraordinarily long time in the ice, even at 140 K. The average migration distance of protons released from H{sub 3}O{sup +} in the ice was estimated to be about two water molecules at {approx}54 K and about six molecules at 100 K. These results indicate that UV-generated hydronium ions can be efficiently stabilized in low-temperature ice. Such metastable hydronium ions may play a significant role in the acid-base chemistry of ice particles in interstellar clouds.
Metastable hydronium ions in UV-irradiated ice.
Moon, Eui-Seong; Kang, Heon
We show that the irradiation of UV light (10-11 eV) onto an ice film produces metastable hydronium (H(3)O(+)) ions in the ice at low temperatures (53-140 K). Evidence of the presence of metastable hydronium ions was obtained by experiments involving adsorption of methylamine onto UV-irradiated ice films and hydrogen-deuterium (H?D) isotopic exchange reaction. The methylamine adsorption experiments showed that photogenerated H(3)O(+) species transferred a proton to the methylamine arriving at the ice surface, thus producing the methyl ammonium ion, which was detected by low energy sputtering method. The H(3)O(+) species induced the H?D exchange of water, which was monitored through the detection of water isotopomers on the surface by using the Cs(+) reactive ion scattering method. Thermal and temporal stabilities of H(3)O(+) and its proton migration activity were examined. The lifetime of the hydronium ions in the amorphized ice was greater than 1 h at ?53 K and decreased to ?5 min at 140 K. Interestingly, a small portion of hydronium ions survived for an extraordinarily long time in the ice, even at 140 K. The average migration distance of protons released from H(3)O(+) in the ice was estimated to be about two water molecules at ?54 K and about six molecules at 100 K. These results indicate that UV-generated hydronium ions can be efficiently stabilized in low-temperature ice. Such metastable hydronium ions may play a significant role in the acid-base chemistry of ice particles in interstellar clouds. PMID:23206024
Detecting swift heavy ion irradiation effects with graphene
NASA Astrophysics Data System (ADS)
Ochedowski, O.; Akcöltekin, S.; Ban-d'Etat, B.; Lebius, H.; Schleberger, M.
In this paper we show how single layer graphene can be utilized to study swift heavy ion (SHI) modifications on various substrates. The samples were prepared by mechanical exfoliation of bulk graphite onto SrTiO3, NaCl and Si(1 1 1), respectively. SHI irradiations were performed under glancing angles of incidence and the samples were analysed by means of atomic force microscopy in ambient conditions. We show that graphene can be used to check whether the irradiation was successful or not, to determine the nominal ion fluence and to locally mark SHI impacts. In case of samples prepared in situ, graphene is shown to be able to catch material which would otherwise escape from the surface.
(Grain boundary and interface kinetics during ion irradiation)
Atwater, H.A.
Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.
[Grain boundary and interface kinetics during ion irradiation
Atwater, H.A.
Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.
Disordering and dissolution of ?' precipitates under ion irradiation
NASA Astrophysics Data System (ADS)
Bourdeau, Françoise; Camus, Eric; Abromeit, Christian; Wollenberger, Heinrich
The stability of the ?' phase of the nickel-base alloy Nimonic PE16 under irradiation with Ni+ ions of 300-keV energy is studied by means of transmission electron microscopy. The disordering of the ?' phase could be followed as a function of fluence. The main finding is the observation of weak but measurable superlattice reflections between 0.1 and 1 dpa after irradiation at room temperature. The superlattice reflections disappear in two steps. Their intensities decrease considerably within a fluence of 0.1 dpa, while weak intensities are observed up to a fluence of 1 dpa. These reflections disappear completely after a fluence of 2 dpa. The results are discussed within a model which considers both disordering and dissolution of precipitates under cascade producing irradiation.
Respiratory gated irradiation system for heavy-ion radiotherapy
Shinichi Minohara; Tatsuaki Kanai; Masahiro Endo; Kouji Noda; Mitsutaka Kanazawa
Purpose: In order to reduce the treatment margin of the moving target due to breathing, we developed a gated irradiation system for heavy-ion radiotherapy.Methods and Materials: The motion of a patient due to respiration is detected by the motion of the body surface around the chest wall. A respiratory sensor was developed using an infrared light spot and a position-sensitive
Effects of high-energy ion irradiation on aluminum creep
E. D. Vorobev; V. R. Regel; D. Senesh; V. A. Skuratov
The creep velocity of thin aluminum samples is studied as a function of loading in samples irradiated by 70 MeV carbon ions. It is shown that the creep velocity can be described by the formulas epsilon-c\\/sup prime\\/\\/sub j\\/approx.e\\/sup v\\/sigma and epsilon-c\\/sup prime\\/\\/sub j\\/approx.(sigma: sigmaâ)\\/sup n\\/. Data on strain ''jumps'' at the instant the beam is turned are discussed.
Magnetization and susceptibility of ion-irradiated granular magnetite films
Weilin Jiang; John S. McCloy; Alan S. Lea; J. A. Sundararajan; Qi Yao; Y. Qiang
Porous granular films of magnetite (Fe3O4) with grains of ˜3 nm in size were prepared using a state-of-the-art nanocluster deposition system. The films are initially superparamagnetic but become magnetized following Si2+ ion irradiation. A significant increase in the grain size and a dramatic change in the microstructure are observed. There are dipolar interactions between the nanoparticles in both the unirradiated
Escherichia coli mutants induced by multi-ion irradiation.
Song, Zhiqing; Luo, Liaofu
Wild-type Escherichia coli K12 strain W3110 was irradiated by 10 keV nitrogen ions. Specifically, irradiation was performed six times by N(+) ions, followed by the selection of lac constitutive mutants, and each time a stable S55 mutant was produced. By sequencing the whole genome, the fine map of S55 was completed. Compared with reference sequences, a total of eighteen single nucleotide polymorphisms (SNPs), two insertions and deletions (Indels), and nine structural variations (SVs) were found in the S55 genome. Among the 18 SNPs, 11 are transversional from A, T or C to G, accounting for 55.6% of point mutations. GCCA insertion occurs in the target gene lacI. Four SNPs, including three in rlpB and one in ygbN, are connected with cell envelope and transport. All nine structural variations of S55 are deletions and contain insertion sequence (IS) elements. Six deleted SVs contain disrupted ISs, nonfunctional pseudogenes, and one more 23 252 bp SV in the Rac prophage region. Overall, our results show that deletion bias observed in E. coli K12 genome evolution is generally related to the deletion of some nonfunctional regions. Furthermore, since ISs are unstable factors in a genome, the multi-ion irradiations that caused these deleted fragments in S55 turn out to be beneficial to genome stability, generating a wider mutational spectrum. Thus, it is possible that the mutation of these genes increases the ability of the E. coli genome to resist etch and damage caused by ion irradiation. PMID:23111758
Ion irradiation induced structural and electrical transition in graphene
Zhou Yangbo; Wang Yifan; Xu Jun; Fu Qiang; Wu Xiaosong; Yu Dapeng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Liao Zhimin [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); Duesberg, Georg S. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); School of Chemistry, Trinity College, Dublin 2 (Ireland)
The relationship between the electrical properties and structure evolution of single layer graphene was studied by gradually introducing the gallium ion irradiation. Raman spectrums show a structural transition from nano-crystalline graphene to amorphous carbon as escalating the degree of disorder of the graphene sample, which is in correspondence with the electrical transition from a Boltzmann diffusion transport to a carrier hopping transport. The results show a controllable method to tune the properties of graphene.
Track Structure in DNA Irradiated with Heavy Ions
Bowman, Michael K.; Becker, David; Sevilla, Michael D.; Zimbrick, John D.
The spatial properties of trapped radicals produced in heavy ion-irradiated solid DNA at 77 K have been probed using pulsed Electron Paramagnetic Double Resonance (PELDOR or DEER) techniques. Salmon testes DNA hydrated to twelve water molecules per nucleotide was irradiated with 40Ar ions of energy 100 MeV/nucleon and LET ranging from 300 to 400 keV/?. Irradiated samples were maintained at cryogenic temperature at all times. PELDOR measurements were made using a refocused echo detection sequence that allows dipolar interaction between trapped radicals to be observed. The EPR spectrum is attributed to electron loss/gain DNA base radicals and neutral carbon-centered radicals that likely arise from sugar damage. We find a radical concentration of 13.5*1018 cm-3 in the tracks and a track radius of 6.79 nm. The cross section of these tracks is 144 nm2 yielding a lineal radical density of 2.6 radicals/nm. Based upon the yields previously determined for particles having calculated LET values of 300-400 keV/mm and our measured lineal density, we obtain an LET of 270 keV/mm, which is in good agreement with the calculated range of values. These measurements of radical density and spatial extent provide the first direct experimental determination of track characteristics in irradiated DNA.
Effect of Ion Irradiation in Cadmium Niobate Pyrochlores
Jiang, Weilin; Weber, William J.; Thevuthasan, Suntharampillai; Boatner, Lynn A.
Irradiation experiments have been performed for cadmium niobate pyrochlore (CdNb2O) single crystals at both 150 and 300 K using 1.0 MeV Au ions over fluences ranging from 0.01 to 0.10 ions/nm. In-situ 3.0 MeV He Rutherford backscattering spectrometry along the <100>-axial channeling direction (RBS/C) has been applied to study the damage states ranging from small defect concentrations to a fully amorphous state. Results show that the crystal can be readily amorphized under the irradiation conditions. Room-temperature recovery of the defects produced at 150 K has been observed, while the defects produced at 300 K are thermally stable at room temperature. Results also indicate that the RBS/C analysis used in this study induced negligible damage in the near-surface regime. In addition, irradiation at and below room temperature using He and C3 ions leads to surface exfoliation at the corresponding damage peaks.
Manipulation of the graphene surface potential by ion irradiation
Ochedowski, O.; Kleine Bussmann, B.; Schleberger, M. [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)] [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Ban d'Etat, B.; Lebius, H. [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France)] [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France)
We show that the work function of exfoliated single layer graphene can be modified by irradiation with swift (E{sub kin}=92 MeV) heavy ions under glancing angles of incidence. Upon ion impact individual surface tracks are created in graphene on silicon carbide. Due to the very localized energy deposition characteristic for ions in this energy range, the surface area which is structurally altered is limited to Almost-Equal-To 0.01 {mu}m{sup 2} per track. Kelvin probe force microscopy reveals that those surface tracks consist of electronically modified material and that a few tracks suffice to shift the surface potential of the whole single layer flake by Almost-Equal-To 400 meV. Thus, the irradiation turns the initially n-doped graphene into p-doped graphene with a hole density of 8.5 Multiplication-Sign 10{sup 12} holes/cm{sup 2}. This doping effect persists even after heating the irradiated samples to 500 Degree-Sign C. Therefore, this charge transfer is not due to adsorbates but must instead be attributed to implanted atoms. The method presented here opens up a way to efficiently manipulate the charge carrier concentration of graphene.
Post-irradiation deformation characteristics of heavy-ion irradiated 304L SS
Cole, J.I. [Washington State Univ., Pullman, WA (United States); Bruemmer, S.M. [Pacific Northwest Lab., Richland, WA (United States)
Post-irradiation deformation behavior in Ni-ion-irradiated 304L stainless steel (SS) is examined as a function of radiation dose and deformation temperature. For similar strain levels, specimens exhibit a transition from dislocation slip to deformation-induced twinning at 25C with increasing radiation dose. At 288C twinning is no longer observed and highly localized slip occurs by the formation of narrow ``channels`` containing a reduced defect density. The observations are discussed in terms of radiation-induced defect character and expected deformation mechanisms.
I-Xe age and trapped Xe components of the Murray /C-2/ chondrite
NASA Astrophysics Data System (ADS)
Niemeyer, S.; Zaikowski, A.
A neutron-irradiated bulk sample of the Murray (C-2) carbonaceous chondrite was etched with H2O2 and then divided into colloidal and non-colloidal fractions. The H2O2 treatment removed about 80% of the trapped Xe and greatly increased variations in the Xe-129/Xe-132 ratio measured in stepwise heating. The colloid showed very little excess Xe-129, but the anti-colloid gave a fairly good I-Xe correlation corresponding to formation 3.7 + or - 2.1 m.y. after Bjurbole. Variations in the trapped Xe component were also observed; most notably the 550 C anti-colloid fraction has large deficiencies relative to AVCC at the heavy isotopes.
High energy ion irradiation effects on mechanical properties of polymeric materials
H. Kudoh; T. Sasuga; T. Seguchi
The authors prepared ion irradiation system to study irradiation effect on polymer materials, and irradiated carbon\\/glass fiber reinforced plastic (CFRP, GFRP), polymethylmethacrylate (PMMA), polyethylene (PE), polytetrafluoroethylene (PTFE), and cellulose tri-acetate (CTA), with high energy ions using cyclotron under vacuum at room temperature. Flexural strength in bending test or elongation at break in tensile test decreased with absorbed dose, but the
Characterization of commercial water treatment membranes modified via ion beam irradiation
Rama Chennamsetty; Isabel Escobar; Xinglong Xu
A commercial sulfonated polysulfone water treatment membrane was modified by ion beam irradiation. After irradiation, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to identify chemical structure changes incurred by the modification. Some of the sulphonic groups on the surface of the membrane were broken due to ion beam irradiation, which resulted in crosslinking of the polymer. These
Characterization of polymeric films subjected to lithium ion beam irradiation
Gary S. Groenewold; W. Roger Cannon; Paul A. Lessing; Recep Avci; Muhammedin Deliorman; Mark Wolfenden; Doug W. Akers; J. Keith Jewell
Two different polymeric materials that are candidate materials for use as binders for mixed uranium–plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C–O and C–C bonds, which furnish radical intermediates that react by radical recombination with Hradical dot and OHradical dot. Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O–methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.
Characterization of polymeric films subjected to lithium ion beam irradiation
NASA Astrophysics Data System (ADS)
Groenewold, Gary S.; Cannon, W. Roger; Lessing, Paul A.; Avci, Recep; Deliorman, Muhammedin; Wolfenden, Mark; Akers, Doug W.; Jewell, J. Keith; Zuck, Larry D.
Two different polymeric materials that are candidate materials for use as binders for mixed uranium-plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C-O and C-C bonds, which furnish radical intermediates that react by radical recombination with Hrad and OHrad . Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O-methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.
Resistivity and morphology of TiSi sub 2 formed on Xe sup + -implanted polycrystalline silicon
Kuwano, H.; Phillips, J.R.; Mayer, J.W. (Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (USA))
Xe ion irradiation of polycrystalline silicon before Ti deposition is found to affect subsequent silicide formation. Silicide films were prepared by implanting 60, 100, or 240 keV Xe{sup +} ions into 500-nm-thick undoped polycrystalline silicon before depositing Ti and annealing in vacuum. Preimplantation altered the subsequent silicide resistivity, x-ray diffraction patterns, and morphology as compared to films prepared on unimplanted polycrystalline Si substrates. We found that minimal TiSi{sub 2} resistivities were achieved at lower temperatures with preimplantation, indicating that the Xe-implanted substrate promotes a lower temperature transition from the metastable C49 phase to the low-resistivity equilibrium C54 phase of TiSi{sub 2}. X-ray diffraction results confirmed the lower temperature formation of the C54 phase with preimplantation. Low-temperature annealing (650 {degree}C, 30 min) of 6{times}10{sup 16} cm{sup {minus}2}, 240 keV Xe{sup +}-implanted samples yielded low-resistivity ({similar to}22 {mu}{Omega} cm) silicide films, while simultaneously annealed samples without preimplantation had resistivity five times higher. Lower doses were effective at lower implant energies, with low resistivity achieved after 725 {degree}C, 30 min annealing for 2{times}10{sup 15} cm{sup {minus}2}, 60 keV Xe{sup +} preimplantation.
Ion irradiation damage in ilmenite at 100 K
Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)
A natural single crystal of ilmenite (FeTiO{sub 3}) was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.
Ion irradiation damage in ilmenite under cryogenic conditions
Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)
A natural single crystal of ilmenite was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 mm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.
Study of ion-irradiated tungsten in deuterium plasma
NASA Astrophysics Data System (ADS)
Khripunov, B. I.; Gureev, V. M.; Koidan, V. S.; Kornienko, S. N.; Latushkin, S. T.; Petrov, V. B.; Ryazanov, A. I.; Semenov, E. V.; Stolyarova, V. G.; Danelyan, L. S.; Kulikauskas, V. S.; Zatekin, V. V.; Unezhev, V. N.
Experimental study aimed at investigation of neutron induced damage influence on fusion reactor plasma facing materials is reported. Displacement damage was produced in tungsten by high-energy helium and carbon ions at 3-10 MeV. The reached level of displacement damage ranged from several dpa to 600 dpa. The properties of the irradiated tungsten were studied in steady-state deuterium plasma on the LENTA linear divertor simulator. Plasma exposures were made at 250 eV of ion energy to fluence 1021-1022 ion/?m2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 ?m layer shown. Deuterium retention in helium-damaged tungsten (ERD) showed its complex behavior (increase or decrease) depending on implanted helium quantity and the structure of the surface layer.
Vibrational spectra and structures of bare and Xe-tagged cationic SinOm+ clusters
NASA Astrophysics Data System (ADS)
Savoca, Marco; Langer, Judith; Harding, Dan J.; Palagin, Dennis; Reuter, Karsten; Dopfer, Otto; Fielicke, André
Vibrational spectra of Xe-tagged cationic silicon oxide clusters SinOm+ with n = 3-5 and m = n, n ± 1 in the gas phase are obtained by resonant infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The SinOm+ clusters are produced in a laser vaporization ion source and Xe complexes are formed after thermalization to 100 K. The clusters are subsequently irradiated with tunable light from an IR free electron laser and changes in the mass distribution yield size-specific IR spectra. The measured IRMPD spectra are compared to calculated linear IR absorption spectra leading to structural assignments. For several clusters, Xe complexation alters the energetic order of the SinOm+ isomers. Common structural motifs include the Si2O2 rhombus, the Si3O2 pentagon, and the Si3O3 hexagon.
Swift heavy ion irradiation of Pt nanocrystals: I. shape transformation and dissolution
Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C. (ANU)
We report on the effects of swift heavy ion irradiation of embedded Pt nanocrystals (NCs), which change from spheres to prolate spheroids to rods upon irradiation. Using a broad range of ion irradiation energies and NC mean sizes we demonstrate that the elongation and dissolution processes are energy and size dependent, attaining comparable levels of shape transformation and dissolution upon a given energy density deposited in the matrix. The NC shape transformation remains operative despite discontinuous ion tracks in the matrix and exhibits a constant threshold size for elongation. In contrast, for ion irradiations in which the ion tracks are continuous, the threshold size for elongation is clearly energy dependent.
Translational energy dependence of reaction mechanism: Xe++CH4?XeH++CH3
Miller, G. D.; Strattan, L. W.; Cole, C. L.; Hierl, Peter M.
The dynamics of the exoergic ion–molecule reaction Xe+(CH4,CH3)XeH+ were studied by chemical accelerator techniques over the relative translational energy range 0.2 to 8 eV. Results of the kinematicmeasurements are reported as scattering intensity...
Absolute photoionization cross sections for Xe{sup 4+}, Xe{sup 5+}, and Xe{sup 6+} near 13.5 nm: Experiment and theory
Aguilar, A.; Gillaspy, J. D.; Gribakin, G. F.; Phaneuf, R. A.; Gharaibeh, M. F.; Kozlov, M. G.; Bozek, J. D.; Kilcoyne, A. L. D. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8421 (United States); Department of Applied Mathematics and Theoretical Physics, Queen's University, Belfast BT7 1NN, Northern Ireland (United Kingdom); Department of Physics, MS 220, University of Nevada, Reno, Nevada 89557-0058 (United States); Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
Absolute photoionization cross-section measurements for a mixture of ground and metastable states of Xe{sup 4+}, Xe{sup 5+}, and Xe{sup 6+} are reported in the photon energy range of 4d{yields}nf transitions, which occur within or adjacent to the 13.5 nm window for extreme ultraviolet lithography light source development. The reported values allow the quantification of opacity effects in xenon plasmas due to these 4d{yields}nf autoionizing states. The oscillator strengths for the 4d{yields}4f and 4d{yields}5f transitions in Xe{sup q+} (q=1-6) ions are calculated using nonrelativistic Hartree-Fock and random phase approximations. These are compared with published experimental values for Xe{sup +} to Xe{sup 3+} and with the values obtained from the present experimental cross-section measurements for Xe{sup 4+} to Xe{sup 6+}. The calculations assisted in the determination of the metastable content in the ion beams for Xe{sup 5+} and Xe{sup 6+}. The experiments were performed by merging a synchrotron photon beam generated by an undulator beamline of the Advanced Light Source with an ion beam produced by an electron cyclotron resonance ion source.
Influence of ion irradiation on iron-chalcogenide superconducting films
NASA Astrophysics Data System (ADS)
Ozaki, Toshinori; Si, Weidong; Zhang, Cheng; Wu, Lijun; Li, Qiang
Iron-chalcogenide superconductors have rather simple crystal structure and no charge reservoir. They also exhibit remarkable properties including small anisotoropy, high upper critical fields, a significant pressure effect on superconductivity. We have grown iron-chalcogenide FeSe0.5Te0.5 (FST) superconducting films on various substrate by pulsed laser deposition. The FST films on CeO2 buffer layer exhibit enhanced Tc (Tconset >20 K, Tczero = 18.0 K), which is about 30% higher than that found in the bulk materials and superior high field performance over the low temperature superconductors.. Recently, we were successful in further enhancement of Jc without Tc degradation by ion irradiation, especially, at high temperature and high magnetic field. The low-energy proton irradiation produces a Jc enhancement of one order of magnitude over the field of 6T//c at 12 K. Extensive TEM studies of the irradiated FST films have been carried out, which revealed an intriguing defect morphology provided by the irradiation. We will discuss the relationship between the superconducting properties and the created defects of the iron-chalcogenide films.
Effects on insulators of swift-heavy-ion irradiation: ion-track technology
NASA Astrophysics Data System (ADS)
Virk, H. S.; Amrita Kaur, S.; Randhawa, G. S.
Polymers (CR-39, SR-86 and Makrofol-KG) and glasses (soda lime and barium phosphate) were irradiated using 0022-3727/31/21/020/img6 ions from the 15UD Pelletron at the NSC, New Delhi. The beam energy was fixed at 60 MeV and the fluence was varied in the range 0022-3727/31/21/020/img7-0022-3727/31/21/020/img8. Irradiation effects were studied using UV-visible and IR spectroscopic techniques. For all the polymer targets there was an increase in absorption due to irradiation mainly in the shorter wavelength region. The change in chemical behaviour of bulk samples is studied by the etching technique. Annealing effects are observed in Makrofol-KG after 75 min heating at 0022-3727/31/21/020/img9C. There is no appreciable change in the optical properties of glasses studied with ion doses in the range 0022-3727/31/21/020/img7-0022-3727/31/21/020/img11. The morphology of heavy-ion latent tracks in insulators is revealed by atomic force microscopy. The applications of ion-track filters produced by swift heavy ions in thin polymer films are also discussed.
Inner-shell photoionization and core-hole decay of Xe and XeF2
NASA Astrophysics Data System (ADS)
Southworth, Stephen; Picón, Antonio; Lehmann, C. Stefan; Wehlitz, Ralf; Cheng, Lan; Stanton, John F.
Molecular effects on inner-shell photoionization and core-hole decay are explored by comparing cross sections and partial ion yields of Xe and XeF2 from Xe 3d and F 1s subshells in the 660-740 eV range. The Xe 3d- ?f continuum shape resonances dominate the total cross sections, but prominent resonances appear in the XeF2 cross section due to excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Relativistic coupled-cluster calculations were performed to identify the subshell ionization thresholds, the LUMO resonances and their oscillator strengths. Comparison of the Xe charge state distributions of the atom and molecule show a general shift to lower charge states in XeF2. The measurements support a model of core-hole decay in which charge is redistributed from Xe to the F ligands and energetic F ions are produced by Coulombic fragmentation. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Dept of Energy, Contract DE-AC02-06CH11357.
Application of ion scattering spectroscopy to measurement of surface potential of MgO thin film under ion irradiation
T. Nagatomi; T. Kuwayama; Y. Takai; K. Yoshino; Y. Morita; M. Kitagawa; M. Nishitani
An experimental approach was proposed for the measurement of the surface potential (SP) induced on an insulator surface during ion irradiation by ion scattering spectroscopy (ISS). The resultant ISS spectra obtained for a MgO thin film of 600 nm thickness on a Si substrate under 950 eV He+ irradiation revealed that the surface is positively charged by approximately 230 V.
Modeling ?-? coincidence spectra of 131m Xe, 133 Xe, 133m Xe, and 135 Xe
D. A. Haas; S. R. Biegalski; K. M. Foltz Biegalski
In support of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), improvements have been made to the model of the Automated\\u000a Radioxenon Sampler\\/Analyzer (ARSA) ?-? coincidence detector for radioxenon monitoring. MCNPX is used to simulate the detector\\u000a response for all the electrons and photons emitted from 131mXe, 133Xe, 133mXe, 135Xe, and 137Cs signals. A MatLab code was written to incorporate the MCNPX results
Application of ion scattering spectroscopy to measurement of surface potential of MgO thin film under ion irradiation
NASA Astrophysics Data System (ADS)
Nagatomi, T.; Kuwayama, T.; Takai, Y.; Yoshino, K.; Morita, Y.; Kitagawa, M.; Nishitani, M.
An experimental approach was proposed for the measurement of the surface potential (SP) induced on an insulator surface during ion irradiation by ion scattering spectroscopy (ISS). The resultant ISS spectra obtained for a MgO thin film of 600nm thickness on a Si substrate under 950eV He+ irradiation revealed that the surface is positively charged by approximately 230V. In addition, the onset energy of a secondary ion peak indicated a SP of approximately 205V. The present results confirmed that ISS is an effective technique for measuring the SP during ion irradiation.
Neovascular glaucoma after helium ion irradiation for uveal melanoma
Kim, M.K.; Char, D.H.; Castro, J.L.; Saunders, W.M.; Chen, G.T.; Stone, R.D.
Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments.
Solid phase epitaxial regrowth of ion beam-amorphized ?-quartz
NASA Astrophysics Data System (ADS)
Roccaforte, F.; Bolse, W.; Lieb, K. P.
Solid phase epitaxial growth of ion beam-amorphized ?-quartz has been studied by means of Rutherford backscattering spectrometry in channeling geometry. ?-quartz single crystals were irradiated with Cs+ and Xe+ ions and annealed in air or in vacuum at 500-900 °C. Complete epitaxial regrowth has been observed in the Cs-irradiated samples, after 875 °C annealing in air. On the other hand, vacuum annealing provided only incomplete regrowth of the amorphous layer, while Xe-irradiated ?-quartz could not be regrown up to 900 °C. The behavior of Cs in the recrystallization process is discussed in terms of the SiO2-network topology.
Multiphoton ionization of iodine atoms and CF 3I molecules by XeCl laser radiation
NASA Astrophysics Data System (ADS)
Lokhman, V. N.; Ogurok, D. D.; Ryabov, E. A.
We report about effective ionization of iodine atoms and CF3I molecules under the action of intense XeCl laser radiation (308 nm). The only ion fragment resulting from the irradiation of the CF3I molecules is the I+ ion. We have studied the influence of the intensity, spectral composition, and polarization of the laser radiation used on the intensity of the ion signal and the shape of its time-of-flight peak. Based on the analysis of the results obtained, we have suggested the mechanism of this effect. The conclusion drawn is that the ionization of the iodine atoms by the ordinary XeCl laser with a nonselective cavity results from a three- (2 + 1)-photon REMPI process. This process is in turn due to the presence of accidental two-photon resonances between various spectral components of the laser radiation and the corresponding intermediate excited states of the iodine atom. The probability of ionization of the atoms from their ground state I(2P3/2) by the radiation of the ordinary XeCl laser is more than two orders of magnitude higher than the probability of their ionization from the metastable state I*(2P1/2). The ionization of the CF3I molecules by the XeCl laser radiation occurs as a result of a four-photon process involving the preliminary one-photon dissociation of these molecules and the subsequent (2 + 1)-photon REMPI of the resultant neutral iodine atoms.
Net sputtering rate due to hot ions in a Ne-Xe discharge gas bombarding an MgO layer
Ho, S.; Tamakoshi, T.; Ikeda, M.; Mikami, Y.; Suzuki, K. [Advanced Research Laboratory, Hitachi, Ltd., Akanuma 2520, Hatoyama-machi, Saitama 350-0395 (Japan)
An analytical method is developed for determining net sputtering rate for an MgO layer under hot ions with low energy (<100 eV) in a neon-xenon discharge gas at near-atmospheric pressure. The primary sputtering rate is analyzed according to spatial and energy distributions of the hot ions with average energy, E{sup h}{sub i}, above a threshold energy of sputtering, E{sub th,i}, multiplied by a yield coefficient. The threshold energy of sputtering is determined from dissociation energy required to remove an atom from MgO surface multiplied by an energy-transfer coefficient. The re-deposition rate of the sputtered atoms is calculated by a diffusion simulation using a hybridized probabilistic and analytical method. These calculation methods are combined to analyze the net sputtering rate. Maximum net sputtering rate due to the hot neon ions increases above the partial pressure of 4% xenon as E{sup h}{sub Ne} becomes higher and decreases near the partial pressure of 20% xenon as ion flux of neon decreases. The dependence due to the hot neon ions on partial pressure and applied voltage agrees well with experimental results, but the dependence due to the hot xenon ions deviates considerably. This result shows that the net sputtering rate is dominated by the hot neon ions. Maximum E{sup h}{sub Ne} (E{sup h}{sub Ne,max} = 5.3 - 10.3 eV) is lower than E{sub th,Ne} (19.5 eV) for the MgO layer; therefore, weak sputtering due to the hot neon ions takes place. One hot neon ion sputters each magnesium and each oxygen atom on the surface and distorts around a vacancy. The ratio of the maximum net sputtering rate is approximately determined by number of the ions at E{sup h}{sub i,max} multiplied by an exponential factor of -E{sub th,i}/E{sup h}{sub i,max}.
Irradiation effect of different heavy ions and track section on the silkworm Bombyx mori
NASA Astrophysics Data System (ADS)
Tu, Zhen-Li; Kobayashi, Yasuhiko; Kiguchi, Kenji; Watanabe, Hiroshi
In order to compare the irradiation effects of different ions, wandering larvae were whole-body exposed or locally irradiated with 50-MeV 4He 2+, 220-MeV 12C 5+, and 350-MeV 20Ne 8+ ions, respectively. For the whole-body-exposed individuals, the survival rates at the cocooning, pupation, and emergence stages all decreased as dose increased, and a range-dependent difference was clearly observed. For local irradiation of ovaries, irradiation effects depend very strongly on the projectile range. In the case of local irradiation of dermal cells by different track sections of heavy ions, the closer the target was to the high-LET section of the track, the more pronounced were the radiation effects. These results indicated that by selectively using ion species and adjusting the irradiation depth to the target, heavy-ion radiosurgery on particular tissues or organs of small experimental animals can be performed more accurately.
[Irradiation with carbon ions for locally recurrent rectal cancer].
Noura, Shingo; Ohue, Masayuki; Miyoshi, Norikatsu; Fukata, Tadafumi; Fujino, Shiki; Sugimura, Keijiro; Akita, Hirofumi; Gotoh, Kunihito; Motoori, Masaaki; Takahashi, Hidenori; Marubashi, Shigeru; Kishi, Kentaro; Fujiwara, Yoshiyuki; Yano, Masahiko; Sakon, Masato
A female patient in her 70s underwent an abdominoperineal resection and bilateral lymph node dissection for advanced lower rectal cancer. The patient did not receive neoadjuvant therapy. In the Japanese classification of colorectal carcinoma (8th Edition), the tumor was a moderately differentiated type 2 adenocarcinoma, and was 4.5 cm in size. Histologically, the tumor was considered to be Stage IIIb (T3N0M0). She received no adjuvant chemotherapy. After 39 months, pelvic computed tomography (CT ) revealed a 29 mm tumor in the right pelvic wall. The patient declined surgery for recurrence so radiotherapy was planned. First, chemotherapy with mFOLFOX6 was administered for 4 courses to reduce tumor size. Consequently, irradiation with carbon ions was given to the site of recurrence at a total dose of 74 GyE in 37 fractions. There were no severe complications. Carcinoembryonic antigen (CEA) level decreased to the lower limit of the normal range from a maximum of 4.9, and no progression of the recurrent tumor was detected on CT for approximately 4 years. Systemic chemotherapy followed by irradiation with carbon ions may be effective for recurrent rectal cancer. PMID:25731305
In situ ion irradiation \\/implantation studies in the HVEM-tandem facility at argonne national laboratory
C. W. Allen; L. L. Funk; E. A. Ryan; A. Taylor
The HVEM-Tandem User Facility at Argonne National Laboratory interfaces two ion accelerators, a 2 MV tandem accelerator and a 650 kV ion implanter, to a 1.2 MV high-voltage electron microscope. This combination allows experiments involving simultaneous ion irradiation\\/ion implantation, electron irradiation and electron microscopy\\/electron diffraction to be performed. In addition the availability of a variety of microscope sample holders permits
Induction of Adaptive Response by High LET Heavy Ion Irradiations in Mice
NASA Astrophysics Data System (ADS)
Wang, Bing; Tanaka, Kaoru; Vares, Guillaume; Shang, Yi; Fujita, Kazuko; Ninomiya, Yasuharu; Nakajima, Tetsuo; Eguchi-Kasai, Kiyomi; Nenoi, Mitsuru
Characterization of radiation-induced adaptive response provides important scientific infor-mation contributing to mechanism research, radiation protection and practical application. In this study, induction of adaptive response by X-rays in combination with high LET irradiations from accelerated heavy ions including carbon, neon, silicon and iron particles was attempted in utero in fetal mice and in vivo in adult mice. In the in utero study, an adaptive response was induced by combination of priming X-irradiations with challenging heavy ion irradiations from carbon or silicon but iron particles; no adaptive response was observable for the combi-nation of priming heavy ion irradiations from carbon, silicon or iron particles with challenging X-irradiations. In the in vivo study, an adaptive response was demonstrated by combination of priming X-irradiations with challenging heavy ion irradiations from carbon or silicon but iron particles; an adaptive response was also observable in the combination of priming heavy ion irradiations from carbon (but neon or silicon) particles with challenging X-irradiations. These findings suggest that induction of adaptive response at whole body level in mice by X-rays in combination with high LET irradiations from accelerated heavy ions is possibly a radiation quality (LET or/and particle) dependent event.
Swift heavy ion irradiation induced texturing in NiO thin films
NASA Astrophysics Data System (ADS)
Mallick, P.; Agarwal, D. C.; Rath, Chandana; Biswal, R.; Behera, D.; Avasthi, D. K.; Kanjilal, D.; Satyam, P. V.; Mishra, N. C.
NiO thin films grown on Si(1 0 0) substrate by electron beam evaporation and sintered at 500 and 700 °C were irradiated with 120 MeV Au 9+ ions. The FCC structure of the sintered films was retained up to the highest fluence (3 × 10 13 ions cm -2) of irradiation. In the low fluence (?1 × 10 13 ions cm -2) regime however, the evolution of the XRD pattern with fluence showed a wide variation, critically depending upon their initial microstructure. Though irradiation is known to induce disorder in the structure, we observe improvement in crystallization and texturing at intermediate fluences of irradiation.
MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations
NASA Astrophysics Data System (ADS)
Prakrajang, K.; Jeynes, J. C. G.; Merchant, M. J.; Kirkby, K.; Kirkby, N.; Thopan, P.; Yu, L. D.
As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.
Oxygen ion irradiation effect on corrosion behavior of titanium in nitric acid medium
NASA Astrophysics Data System (ADS)
Ningshen, S.; Kamachi Mudali, U.; Mukherjee, P.; Barat, P.; Raj, Baldev
The corrosion assessment and surface layer properties after O 5+ ion irradiation of commercially pure titanium (CP-Ti) has been studied in 11.5 N HNO 3. CP-Ti specimen was irradiated at different fluences of 1 × 10 13, 1 × 10 14 and 1 × 10 15 ions/cm 2 below 313 K, using 116 MeV O 5+ ions source. The corrosion resistance and surface layer were evaluated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and glancing-angle X-ray diffraction (GXRD) methods. The potentiodynamic anodic polarization results of CP-Ti revealed that increased in ion fluence (1 × 10 13-1 × 10 15 ions/cm 2) resulted in increased passive current density due to higher anodic dissolution. SEM micrographs and GXRD analysis corroborated these results showing irradiation damage after corrosion test and modified oxide layer by O 5+ ion irradiation was observed. The EIS studies revealed that the stability and passive film resistance varied depending on the fluence of ion irradiation. The GXRD patterns of O 5+ ion irradiated CP-Ti revealed the oxides formed are mostly TiO 2, Ti 2O 3 and TiO. In this paper, the effects of O 5+ ion irradiation on material integrity and corrosion behavior of CP-Ti in nitric acid are described.
Morphological change of multiwalled carbon nanotubes through high-energy (MeV) ion irradiation
Kim, H.M.; Kim, H.S.; Park, S.K.; Joo, J.; Lee, T.J.; Lee, C.J. [Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); Department of Nanotechnology, Hanyang University, Seoul 133-791 (Korea, Republic of)
Multiwalled carbon nanotubes (MWCNTs) were expanded by 2.5 times in diameter through high-energy (MeV) ion irradiation. Pristine MWCNTs were synthesized onto SiO{sub 2} substrate by chemical vapor deposition. The 4 MeV Cl{sup 2+} ions with a dose of 3x10{sup 16} ions/cm{sup 2} were irradiated on MWCNTs. From high-resolution transmission electron microscopy (HR-TEM) images, the average diameter of the high-energy-ion-irradiated MWCNTs was {approx}180 nm, while that of the pristine MWCNTs was {approx}70 nm. The wall thickness of the pristine and the high-energy-ion-irradiated MWCNT samples was {approx}20 nm and 40-50 nm, respectively. We observed the clear formation of nanocompartments with bamboolike structure inside the tubes after ion irradiation. The amorphous carbon structure in the ion-irradiated MWCNT shells was observed from Raman spectra. Based on the results of HR-TEM and Raman spectra, the expansion of the systems represents morphological transition from crystalline graphite structure to amorphous carbon or finite sized graphite structure due to the ion impact. We suggest that high-energy ion irradiation can be useful for the modification of MWCNT structures.
Thermal neutron activation cross sections for Kr and Xe isotopes
E. Kondaiah; N. Ranakumar; R. W. Fink
Quinol-clathrates of Kr and Xe have been used as solid targets for neutron activation for the first time, and 16 (n, gamma) cross sections have been determined with thermal neutrons. The epithermal neutron contribution has been taken into account by irradiating Cd covered samples. Four isomer cross-section ratios for Xe isotopes and one for Kr have also been obtained. In
Characterization of ion track morphology formed by swift heavy ion irradiation in silicon oxynitride films
NASA Astrophysics Data System (ADS)
Mota-Santiago, P.; Schauries, D.; Nadzri, A.; Vora, K.; Ridgway, M. C.; Kluth, P.
Amorphous silicon oxynitride (SiOxNy) possess interesting optical and mechanical properties. Here, we present direct evidence for the formation of ion tracks in 1 µm thick silicon oxynitride of different stoichiometries. The tracks were created by irradiation with 185 MeV Au13+ ions. The samples were studied using spectral reflectometry and Rutherford backscattering spectrometry (RBS), with the track morphology characterised by means of small angle X-ray scattering (SAXS). The radial density of the ion tracks resembles a core-shell structure with a typical radius of ~ 1.8 + 2.4 nm in the case of Si3N4 and 2.3 + 3.2 nm for SiO2.
Response of nanostructured ferritic alloys to high-dose heavy ion irradiation
Parish, Chad M.; White, Ryan M.; LeBeau, James M.; Miller, Michael K.
A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at -100°C and 750°C, as well as pre-irradiation reference material. Irradiation at -100°C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti-Y-O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750°C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr-W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.
Heavy ion and X-ray irradiation alter the cytoskeleton and cytomechanics of cortical neurons.
Du, Yuting; Zhang, Jie; Zheng, Qian; Li, Mingxin; Liu, Yang; Zhang, Baoping; Liu, Bin; Zhang, Hong; Miao, Guoying
Heavy ion beams with high linear energy transfer exhibit more beneficial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irradiation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy; subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunofluorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was significantly decreased, and there was evidence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our findings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation. PMID:25206772
Magnetic strip patterns induced by focused ion beam irradiation
Makarov, D.; Tibus, S. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Rettner, C. T. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95123 (United States); Thomson, T.; Terris, B. D. [San Jose Research Center, Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, California 95135 (United States); Schrefl, T. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Albrecht, M. [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)
Focused ion beam exposure was used to locally alter the magnetic properties of a continuous Co/Pd multilayer film with perpendicular magnetic anisotropy. The saturation magnetization, coercivity, and magnetic anisotropy of the films can be tuned by Ga irradiation depending on exposure dose. As a result, a periodic strip pattern consisting of 80 nm wide exposed strips which are magnetically soft, separated by 170 nm wide magnetically hard, unexposed areas was created. Due to strong magnetostatic coupling between the strips, a number of magnetic domain configurations could be stabilized and these have been observed by magnetic force microscopy and magneto-optic Kerr effect measurements. The magnetic domain configurations and their reversal behavior were investigated by micromagnetic simulations as a function of exposure dose and strip period.
Ion-irradiation studies of cascade damage in metals
Averback, R.S.
Ion-irradiation studies of the fundamental aspects of cascade damage in metals are reviewed. The emphasis of these studies has been the determination of the primary state of damage (i.e. the arrangement of atoms in the cascade region prior to thermal migration of defects). Progress has been made towards understanding the damage function (i.e. the number of Frenkel pairs produced as a function of primary recoil atom energy), the spatial configuration of vacancies and interstitials in the cascade and the cascade-induced mixing of atoms. It is concluded for these studies that the agitation of the lattice in the vicinity of energetic displacement cascades stimulates the defect motion and that such thermal spike motion induces recombination and clustering of Frenkel defects. 9 figures.
Sympathetic ophthalmia complicating helium ion irradiation of a choroidal melanoma
Fries, P.D.; Char, D.H.; Crawford, J.B.; Waterhouse, W.
Sympathetic ophthalmia was diagnosed 49 months after helium ion irradiation of a left choroidal melanoma. The patient maintained good vision until 18 months after therapy, when she developed neovascular glaucoma. This complication required multiple therapeutic procedures, including topical anti-inflammatory and antiglaucomatous drops, 360 degrees peripheral panretinal cryoblation, and a single 180 degrees application of inferior cyclocryotherapy over a 2 1/2-year period. Four weeks after the cyclocryotherapy, inflammation was noted in both eyes, and, one month later, enucleation of the left sympathogenic eye was performed. Serial histopathologic sections showed a full-thickness, fibrovascular, scleral scar and tantalum marker ring suture without uveal incarceration. Penetrating surgical trauma, a uveal melanoma, and multiple nonpenetrating treatments resulted in the development of sympathetic ophthalmia.
Superlattice-like stacking fault array in ion-irradiated GaN
Ishimaru, Dr. Manabu [Osaka University; Usov, Igor Olegovich [ORNL; Zhang, Yanwen [ORNL; Weber, William J [ORNL
Controlling defects in crystalline solids is of technological importance for realizing desirable materials properties. Irradiation with energetic particles is useful for designing the spatial distribution and concentration of defects in materials. Here, we performed ion irradiation into hexagonal GaN with the wurtzite structure and demonstrated the spontaneous formation of superlattice-like stacking fault arrays. It was found that the modulation period can be controlled by irradiation conditions and post-irradiation heat treatments.
Shape transformation of Sn nanocrystals induced by swift heavy-ion irradiation and the necessity of a molten ion track
Giulian, R.; Araujo, L. L.; Sprouster, D. J.; Kluth, P.; Byrne, A. P.; Ridgway, M. C. [Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Kremer, F.; Fichtner, P. F. P. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Ciaxa Postal 1501, CEP 91501-970, Porto Alegre, Rs (Brazil)
We report on the spherical to rodlike shape transformation of Sn nanocrystals (NCs) embedded in amorphous SiO{sub 2} following irradiation with 185 MeV Au ions. Consistent with previous reports for other metals, transmission electron microscopy demonstrates that under irradiation, Sn NCs larger than a critical size (11 nm) elongate parallel to the incident ion direction, while smaller particles remain spherical. Irradiation-induced NC dissolution is significant, as evident from the formation of smaller NCs in place of their original larger counterparts. Using formation conditions that yield Sn NCs at the amorphous-SiO{sub 2}/crystalline-Si interface, we show that the irradiation-induced shape change occurs only within the SiO{sub 2} layer, in the direction opposite to that of the incident ions. We suggest this demonstrates the necessity of a molten ion track and provides further evidence for an elongation process involving NC melting and flow.
Cation disordering in magnesium aluminate spinel crystals induced by electron or ion irradiation
Takeshi Soeda; Syo Matsumura; Chiken Kinoshita; Nestor J Zaluzec
Structural changes in magnesium aluminate spinel (MgO·nAl2O3) single crystals, which were irradiated with 900 keV electrons or 1 MeV Ne+ ions at 873 K, were examined by electron channeling enhanced X-ray microanalysis. Unirradiated MgO·Al2O3 has a tendency to form the normal spinel configuration, where Mg2+ ions and Al3+ ions occupy mainly the tetrahedral and the octahedral sites, respectively. Electron irradiation
High-fluence hyperthermal ion irradiation of gallium nitride surfaces at elevated temperatures
NASA Astrophysics Data System (ADS)
Finzel, A.; Gerlach, J. W.; Lorbeer, J.; Frost, F.; Rauschenbach, B.
Wurtzitic GaN films deposited on 6H-SiC(0001) substrates by ion-beam assisted molecular-beam epitaxy were irradiated with hyperthermal nitrogen ions with different fluences at different substrate temperatures. In situ observations with reflection high energy electron diffraction showed that during the irradiation process the surface structure of the GaN films changed from two dimensional to three dimensional at elevated temperatures, but not at room temperature. Atomic force microscopy revealed an enhancement of nanometric holes and canyons upon the ion irradiation at higher temperatures. The roughness of the irradiated and heated GaN films was clearly increased by the ion irradiation in accordance with x-ray reflectivity measurements. A sole thermal decomposition of the films at the chosen temperatures could be excluded. The results are discussed taking into account temperature dependent sputtering and surface uphill adatom diffusion as a function of temperature.
Effect of swift heavy ion irradiation in FePt system
NASA Astrophysics Data System (ADS)
Kavita, S.; Reddy, V. Raghavendra; Gupta, Ajay; Avasthi, D. K.
The present study reports the effects of swift heavy ion irradiation in FePt system in different forms viz., uniform alloy film, multilayer, and nano-particles in non-magnetic medium. The FePt alloy film, Fe/Pt multilayer and FePt nano-particles in silver matrix with partial L10 ordering, are prepared by ion beam sputtering method and subsequent vacuum annealing at 450 °C for 1 h. These samples are irradiated with swift heavy ions in order to study structural changes induced due to electronic energy loss by the bombarding ions. X-ray diffraction and magneto-optical Kerr effect are used for the characterisation of the unirradiated and irradiated films. It is observed that irradiation results in partial destruction of L10 ordering. Irradiation effects are more pronounced in the case of nano-particles and multilayers as compared to that of continuous alloy film. The results are discussed using thermal spike model.
Effect of irradiation by heavy ions on the nanostructure of perspective materials for nuclear power plants
NASA Astrophysics Data System (ADS)
Rogozhkin, S. V.; Aleev, A. A.; Zaluzhnyi, A. G.; Kuibida, R. P.; Kulevoi, T. V.; Nikitin, A. A.; Orlov, N. N.; Chalykh, B. B.; Shishmarev, V. B.
An imitation experimental technique on the irradiation with heavy ions of structural materials of nuclear power plants using tomographic atom probe analysis has been elaborated. The scheme of irradiation of specimens for atom probe analysis has been realized on a MEVVA ion source of an TIPr accelerator (ITEP) with ion energy 75 keV per charge. Test experiments with irradiation and analysis of samples of the EK-181 steel by aluminum ions to a fluence of ˜2 × 1015 ion/cm2 have been performed. Experiments on the Fe-ion irradiation of the samples of ODS EUROFER perspective steel for fission and fusion reactors to different damaging doses have been carried out. The analysis of distribution of different chemical elements in the volumes tested has revealed that under ion irradiation a change in the composition of nanosized clusters, which are present in the initial material takes place. Comparison of the data obtained with the results of reactor irradiation of the ODS EUROFER steel has been carried out. These data testify a correspondence between nanoscale changes in the steels oxide dispersion strengthened in imitation experiments and under the conditions of reactor irradiation.
Swift heavy ions induced irradiation effects in monolayer graphene and highly oriented pyrolytic graphite
NASA Astrophysics Data System (ADS)
Zeng, J.; Yao, H. J.; Zhang, S. X.; Zhai, P. F.; Duan, J. L.; Sun, Y. M.; Li, G. P.; Liu, J.
Monolayer graphene and highly oriented pyrolytic graphite (HOPG) were irradiated by swift heavy ions (209Bi and 112Sn) with the fluence between 1011 and 1014 ions/cm2. Both pristine and irradiated samples were investigated by Raman spectroscopy. It was found that D and D? peaks appear after irradiation, which indicated the ion irradiation introduced damage both in the graphene and graphite lattice. Due to the special single atomic layer structure of graphene, the irradiation fluence threshold ?th of the D band of graphene is significantly lower (<1 × 1011 ions/cm2) than that (2.5 × 1012 ions/cm2) of HOPG. The larger defect density in graphene than in HOPG indicates that the monolayer graphene is much easier to be damaged than bulk graphite by swift heavy ions. Moreover, different defect types in graphene and HOPG were detected by the different values of ID/ID?. For the irradiation with the same electronic energy loss, the velocity effect was found in HOPG. However, in this experiment, the velocity effect was not observed in graphene samples irradiated by swift heavy ions.
The potential application of ultra-nanocrystalline diamond films for heavy ion irradiation detection
NASA Astrophysics Data System (ADS)
Chen, Huang-Chin; Chen, Shih-Show; Wang, Wei-Cheng; Lee, Chi-Young; Guo, Jinghua; Lin, I.-Nan; Chang, Ching-Lin
The potential of utilizing the ultra-nanocrystalline (UNCD) films for detecting the Au-ion irradiation was investigated. When the fluence for Au-ion irradiation is lower than the critical value (fc = 5.0 × 1012 ions/cm2) the turn-on field for electron field emission (EFE) process of the UNCD films decreased systematically with the increase in fluence that is correlated with the increase in sp2-bonded phase (?*-band in EELS) due to the Au-ion irradiation. The EFE properties changed irregularly, when the fluence for Au-ion irradiation exceeds this critical value. The transmission electron microscopic microstructural examinations, in conjunction with EELS spectroscopic studies, reveal that the structural change preferentially occurred in the diamond-to-Si interface for the samples experienced over critical fluence of Au-ion irradiation, viz. the crystalline SiC phase was induced in the interfacial region and the thickness of the interface decreased. These observations implied that the UNCD films could be used as irradiation detectors when the fluence for Au-ion irradiation does not exceed such a critical value.
Electron-ion collision rates in atomic clusters irradiated by femtosecond laser pulses
M. Moll; P. Hilse; M. Schlanges; Th Bornath; V. P. Krainov
In atomic clusters irradiated by femtosecond laser pulses, plasmas with high density and high temperature are created. The heating is mainly caused by inverse bremsstrahlung, i.e. determined by electron-ion collisions. In the description of the scattering of electrons on noble gas ions in such plasmas, it is important to account for the inner structure of the ions and the screening
Microstructural stability of a self-ion irradiated lanthana-bearing nanostructured ferritic steel
NASA Astrophysics Data System (ADS)
Pasebani, Somayeh; Charit, Indrajit; Burns, Jatuporn; Alsagabi, Sultan; Butt, Darryl P.; Cole, James I.; Price, Lloyd M.; Shao, Lin
Thermally stable nanofeatures with high number density are expected to impart excellent high temperature strength and irradiation stability in nanostructured ferritic steels (NFSs) which have potential applications in advanced nuclear reactors. A lanthana-bearing NFS (14LMT) developed via mechanical alloying and spark plasma sintering was used in this study. The sintered samples were irradiated by Fe2+ ions to 10, 50 and 100 dpa at 30 °C and 500 °C. Microstructural and mechanical characteristics of the irradiated samples were studied using different microscopy techniques and nanoindentation, respectively. Overall morphology and number density of the nanofeatures remained unchanged after irradiation. Average radius of nanofeatures in the irradiated sample (100 dpa at 500 °C) was slightly reduced. A notable level of irradiation hardening and enhanced dislocation activity occurred after ion irradiation except at 30 °C and ?50 dpa. Other microstructural features like grain boundaries and high density of dislocations also provided defect sinks to assist in defect removal.
Surface Hardness Improvement of PMMA by Low Energy Ion Irradiation and Electron Irradiation
NASA Astrophysics Data System (ADS)
Sakurabayashi, Yuya; Masaki, Takahiro; Iwao, Toru; Yumoto, Motoshige
Surface modification of PMMA(polymethylmethacrylate) was carried out by irradiation of low energy ion and/or electron, which is expected to improve the surface hardness by introduction of a thin modified layer. Surface hardness was measured by using the nanoindentation test. To clarify the structure and the properties of the modified layer, depth profiles of composition and chemical bonds were analyzed using XPS(X-ray photoelectron spectroscopy). Forming cross-linking structure that contributed to the surface hardness was analyzed using dyeing method. From these results, it was confirmed that surface hardness increased and existence of cross-linking structure. It was suggested that the existence of the structure brought about the increase of surface hardness, and showed the utility of the dyeing method.
He{sup +} ion irradiation study of continuous and patterned Co/Pd multilayers
Parekh, Vishal; Smith, Darren; E, Chunsheng; Rantschler, James; Khizroev, Sakhrat; Litvinov, Dmitri [Center for Nanomagnetic Systems, University of Houston, Houston, Texas 77204 (United States); Electrical Engineering, University of California--Riverside, Riverside, California 92521 (United States); Center for Nanomagnetic Systems, University of Houston, Houston, Texas 77204 (United States); Sentorix, Inc., Pearland, TX 77584 (United States)
Ion irradiation of continuous and patterned (Co/Pd){sub n} magnetic multilayer films has been studied as a mean to control magnetic anisotropy as well as to evaluate possible ion irradiation damage involved in ion-beam proximity lithography patterning. The coercivity of patterned medium was found to decrease from 11 kOe for as patterned samples to 0.3 kOe for samples with 800 {mu}C/cm{sup 2} ion irradiation. Remnant squareness of the patterned samples remained essentially unchanged. As the number of bilayers increases in the sample, the effects vary, suggesting that several mechanisms of damage occur. Significantly, for typical irradiation doses used in ion-beam proximity lithography, no measurable alteration of magnetic properties was observed.
Fabrication of porous silicon nanotips by using argon ion-beam irradiation
NASA Astrophysics Data System (ADS)
Zhan, Chang-Yong; Zou, Yu; Wu, Jian-Chun; Chu, P. K.
Porous silicon nanotips (NTs) are promising in many applications such as field emission, superhydrophobicity, solar cells and photoluminescence. Ion irradiation can create unique nanostructures in many types of materials at room temperature, and this paper reports the surface morphology of porous silicon irradiated by an Ar+ ion beam. Different porous silicons are irradiated, and the effects of the ion's angle of incidence on the porous silicon nanostructure are investigated. High-density NTs of less than 50 nm in size are observed on the porous silicon. The NT size increases, but NT density decreases, with increasing pore size. The orientation of the NTs can be controlled by adjusting the ion impact. Our results reveal that the NTs located at the thick wall between pores and charges created on the tip during Ar+ ion irradiation are beneficial to the formation of the NTs.
The JANNUS Saclay facility: A new platform for materials irradiation, implantation and ion beam analysis
NASA Astrophysics Data System (ADS)
Pellegrino, S.; Trocellier, P.; Miro, S.; Serruys, Y.; Bordas, É.; Martin, H.; Chaâbane, N.; Vaubaillon, S.; Gallien, J. P.; Beck, L.
The third accelerator of the multi-ion irradiation platform JANNUS (Joint Accelerators for Nanosciences and NUclear Simulation), a 6SDH-2 Pelletron from National Electrostatic Corporation, Middleton was installed at Saclay in October 2009. The first triple beam irradiation combining Fe, He and H ion beams has been performed in March 2010. In the first part of this paper, we give a technical description of the triple beam facility, its performances and experimental capabilities. Typically, damage dose up to 100 dpa can be reached in 10 h irradiation with heavy ion beams, with or without simultaneous bombardment by protons, helium-4 ions or any other heavy ion beam. In the second part of this paper, we illustrate some IBA results obtained after irradiation and implantation experiments.
Simulations of Xe and U diffusion in UO2
Andersson, Anders D. [Los Alamos National Laboratory; Vyas, Shyam [Los Alamos National Laboratory; Tonks, Michael R. [Idaho National Laboratory; Casillas, Luis [Los Alamos National Laboratory; Uberuaga, Blas P. [Los Alamos National Laboratory; Millett, Paul [Idaho National Laboratory
Diffusion of xenon (Xe) and uranium (U) in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. Based on the vacancy and cluster diffusion mechanisms established from density functional theory (DFT) calculations, we derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2}. In order to capture the effects of irradiation, vacancies (Va) are explicitly coupled to the Xe and U dynamics. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the bulk diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries, which were derived from atomistic calculations. The diffusion and segregation models were implemented in the MOOSE-Bison-Marmot (MBM) finite element (FEM) framework and the Xe/U redistribution was simulated for a few simple microstructures.
Microstructure and thermal desorption of deuterium in heavy-ion-irradiated pure tungsten
NASA Astrophysics Data System (ADS)
Watanabe, Hideo; Futagami, Naoki; Naitou, Shiori; Yoshida, Naoaki
To understand the fundamental processes of deuterium retention and desorption of irradiated plasma facing materials, thermal desorption of deuterium in pure W with and without ion irradiation up to 2 dpa by 2.4 MeV Cu2+ have been investigated. After the ion irradiation at room temperature, high density of small interstitial typed dislocation loops and also nano-voids due to cascade collisions were detected by TEM observation. Thermal desorption of spectra of D showed that fine vacancy clusters are formed even at low fluence and at room temperature irradiation, these defects act as the strong trapping center of deuterium in the temperature range of 660-900 K.
Diamond-like carbon sputtering by laser produced Xe plasma
NASA Astrophysics Data System (ADS)
Amano, Sho; Inoue, Tomoaki
The sputtering of diamond-like carbon (DLC) was investigated using Xe ion bombardment from the laser plasma X-ray source (LPX). The LPX we developed uses a solid Xe target and emits UV-X-rays and Xe ions. Using the LPX as an ion source, we measured etching depths of DLC, Ru, and Au films using a quartz crystal microbalance (QCM) to determine their ion sputtering rates at incident angles of 0° and 70°. The calculated results by the SRIM code were able to predict the measured results, except for the case of the DLC film at 0° incident. Our measured result indicated that the DLC sputtering at 0° was ten times larger than previously reported data, in which an ion gun was used. We consider that the difference was a characteristic effect of the laser plasma, and can be explained as a synergistic effect of ion bombardment and UV radiation from the Xe plasma.
In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene
NASA Astrophysics Data System (ADS)
Pan, C.-T.; Hinks, J. A.; Ramasse, Q. M.; Greaves, G.; Bangert, U.; Donnelly, S. E.; Haigh, S. J.
Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy.
Ion beam-induced anisotropic plastic deformation at 300 keV
T. van Dillen; A. Polman; C. M. van Kats; A. van Blaaderen
Contrary to earlier predictions, ion irradiation at energies as low as 300 keV causes dramatic anisotropic plastic deformation of silica glass. Spherical colloidal silica particles with diameters of 125, 305, and 1030 nm were irradiated with Xe ions at energies in the range 0.3-4.0 MeV at temperatures between 85 and 380 K. Irradiation-induced anisotropic plastic deformation changes the colloid shape
Ion beam-induced anisotropic plastic deformation at 300 keV
T. van Dillen; A. Polman; C. M. van Kats; A. van Blaaderen
Contrary to earlier predictions, ion irradiation at energies as low as 300 keV causes dramatic anisotropic plastic deformation of silica glass. Spherical colloidal silica particles with diameters of 125, 305, and 1030 nm were irradiated with Xe ions at energies in the range 0.3–4.0 MeV at temperatures between 85 and 380 K. Irradiation-induced anisotropic plastic deformation changes the colloid shape
Microstructural evolution in nickel alloy C-276 after Ar-ion irradiation at elevated temperature
Jin, Shuoxue [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); He, Xinfu [China Institute of Atomic Energy, Beijing 102413 (China)] [China Institute of Atomic Energy, Beijing 102413 (China); Li, Tiecheng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Ma, Shuli; Tang, Rui [Nuclear Power Institute of China, Chengdu 610041 (China)] [Nuclear Power Institute of China, Chengdu 610041 (China); Guo, Liping, E-mail: firstname.lastname@example.com [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)
In present work, the irradiation damage in nickel-base alloy C-276 irradiated with Ar-ions was studied. Specimens of C-276 alloy were subjected to an irradiation of Ar-ions (with 120 keV) to dose levels of 6 and 10 dpa at 300 and 550 Degree-Sign C, respectively. The size distributions and densities of dislocation loops caused by irradiation were investigated with transmission electron microscopy. Irradiation hardening due to the formation of the loops was calculated using the dispersed barrier-hardening model, showing that irradiation hardening was greatest at 300 Degree-Sign C/6 dpa. The microstructure evolution induced by Ar-ion irradiation (0-10 dpa) in nickel-base alloy C-276 has been studied using a multi-scale modeling code Radieff constructed based on rate theory, and the size of dislocation loops simulated by Radieff was in good agreement with the experiment. - Highlights: Black-Right-Pointing-Pointer High density of dislocation loops appeared after Ar ions irradiation. Black-Right-Pointing-Pointer Irradiation hardening due to the formation of loops was calculated by the DBH model. Black-Right-Pointing-Pointer Size of loops simulated by Radieff was in good agreement with the experiment.
Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films
Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Sundaravel, Balakrishnan [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, Sankarakumar [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)
The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4x10{sup 13} ions/cm{sup 2} is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 deg. C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.
Investigation of the effect of low energy ion beam irradiation on mono-layer graphene
Xu, Yijun [College of Physics science and technology, Soochow University, Suzhou215006 (China) [College of Physics science and technology, Soochow University, Suzhou215006 (China); II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Zhang, Kun; Brüsewitz, Christoph; Hofsäss, Hans Christian [II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany)] [II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany); Wu, Xuemei [College of Physics science and technology, Soochow University, Suzhou215006 (China) [College of Physics science and technology, Soochow University, Suzhou215006 (China); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)
In this paper, the effect of low energy irradiation on mono-layer graphene was studied. Mono-layer graphene films were irradiated with B, N and F ions at different energy and fluence. X-ray photoelectron spectroscopy indicates that foreign ions implanted at ion energies below 35 eV could dope into the graphene lattice and form new chemical bonds with carbon atoms. The results of Raman measurement indicate that ion beam irradiation causes defects and disorder to the graphene crystal structure, and the level of defects increases with increasing of ion energy and fluence. Surface morphology images also prove that ion beam irradiation creates damages to graphene film. The experiment results suggest that low-energy irradiation with energies of about 30 eV and fluences up to 5·10{sup 14} cm{sup ?2} could realize small amount of doping, while introducing weak damage to graphene. Low energy ion beam irradiation, provides a promising approach for controlled doping of graphene.
Electronic spectroscopy of I2-Xe complexes in solid Krypton
NASA Astrophysics Data System (ADS)
Hulkko, Eero; Ahokas, Jussi; Lindgren, Johan; Myllyperkiö, Pasi; Pettersson, Mika
In the present work, we have studied ion-pair states of matrix-isolated I2 with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I2-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I2 with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm-1 from the X ? D transition of I2. Observed redshift can be explained by symmetry breaking of ion-pair states within the I2-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I2 ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I2 dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.
{alpha}-AlMnSi phase to a bcc structure by Xe{sup +} ion-beam irradiation
Guo, Y.X.; Wang, L.M.; Ewing, R.C. [Univ. of New Mexico, Albuquerque, NM (United States)
AlMnSi alloy system has attracted great attentions since the first report on the icosahedral quasicrystal materials in 1984. The rapidly quenched AlMnSi alloy around the stoichiometry of the {alpha}-AlMnSi phase ({alpha}-phase below) may form icosahedral quasicrystals. And the structure unit of the {alpha}-phase is of near icosahedral symmetry. The {alpha}-phase has a cubic structure with space group Pm3 (a=1.268 nm). In each unit cell there are 138 atoms. The most important structure unit in this phase is the so-called MacKay icosahedron. In such a structure unit, 12 Al atoms are decorating the vertices of an icosahedron. Surrounding this icosahedron is another same oriented icosahedron of 12 Mn atoms, which is about twice the diameter of the former. Furthermore, 30 Al atoms define a shell outside the two inner icosahedra with each atom sitting distorted and are connected along those of their three fold axes that coincide with the <111> direction of the cubic lattice. The two triangular faces of the Mn icosahedron make up an Mn octahedron. Hence, two MacKay icosahedra define two basic positions as if in a bcc cell with a total of 108 atoms. The rest 30 atoms of light elements (Al or Si) in the structure serve as glue atoms that fill up gaps among the slightly distorted icosahedra. Electron diffraction pattern of this primitive cubic phase is shown in figure 1a, which is in [001] zone axis.
Incoherent twin boundary migration induced by ion irradiation in Cu
Li, N.; Misra, A. [Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, J.; Wang, Y. Q. [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Serruys, Y. [CEA, DEN, Service de Recherches de Metallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Nastasi, M. [Nebraska Center for Energy Sciences Research, University of Nebraska, Lincoln, Nebraska 68588 (United States)
Grain boundaries can act as sinks for radiation-induced point defects. The sink capability is dependent on the atomic structures and varies with the type of point defects. Using high-resolution transmission electron microscopy, we observed that {Sigma}3{l_brace}112{r_brace} incoherent twin boundary (ITB) in Cu films migrates under Cu{sup 3+} ion irradiation. Using atomistic modeling, we found that {Sigma}3{l_brace}112{r_brace} ITB has the preferred sites for adsorbing interstitials and the preferential diffusion channels along the Shockley partial dislocations. Coupling with the high mobility of grain boundary Shockley dislocations within {Sigma}3{l_brace}112{r_brace} ITB, we infer that {Sigma}3{l_brace}112{r_brace} ITB migrates through the collective glide of grain boundary Shockley dislocations, driven by a concurrent reduction in the density of radiation-induced defects, which is demonstrated by the distribution of nearby radiation-induced defects.
Nano-porosity in GaSb induced by swift heavy ion irradiation
Kluth, P., E-mail: email@example.com; Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Sullivan, J.; Weed, R. [ARC Centre for Antimatter-Matter Studies, AMPL, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Li, W.; Ewing, R. C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States)
Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.
Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories
NASA Technical Reports Server (NTRS)
Oldham, Timothy R.; Berg, Melanie; Friendlich, Mark; Wilcox, Ted; Seidleck, Christina; LaBel, Kenneth A.; Irom, Farokh; Buchner, Steven P.; McMorrow, Dale; Mavis, David G.; Eaton, Paul H.; Castillo, James
A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed.
Evolution of surface morphology of NiO thin films under swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Mallick, P.; Rath, Chandana; Majumder, S.; Biswal, R.; Agarwal, D. C.; Varma, Shikha; Avasthi, D. K.; Satyam, P. V.; Mishra, N. C.
NiO nanoparticle thin films grown on Si substrates were irradiated by 107 MeV Ag 8+ ions. The films were characterized by glancing angle X-ray diffraction and atomic force microscopy. Ag ion irradiation was found to influence the shape and size of the nanoparticles. The pristine NiO film consisted of uniform size (˜100 nm along major axis and ˜55 nm along minor axis) elliptical particles, which changed to also of uniform size (˜63 nm) circular shape particles on irradiation at a fluence of 3 × 10 13 ions cm -2. Comparison of XRD line width analysis and AFM data revealed that the particles in the pristine films are single crystalline, which turn to polycrystalline on irradiation with 107 MeV Ag ions.
Swift heavy ion irradiation induced nanoparticle formation in CeO 2 thin films
NASA Astrophysics Data System (ADS)
Varshney, Mayora; Sharma, Aditya; Kumar, Ravi; Verma, K. D.
Nanoparticle formation in the, rf-sputtering grown, polycrystalline CeO 2 thin films is achieved by the swift heavy ion (SHI) irradiation. Crystal structure and phases present in the as-grown and irradiated thin films are investigated by the X-ray diffraction (XRD) measurements. Irradiation induced formation of spherically shaped nanostructures, on the film surface, is confirmed by the atomic force microscopy (AFM). The Raman spectra of the irradiated samples show increased line-width and peak position shifting in the Raman active mode (F 2g) of CeO 2, indicative of the nanocrystallization in the irradiated CeO 2 thin films. Formation of nanostructures in the irradiated samples is also briefly discussed in the light of ion energy and energy loss mechanisms.
In situ study of ion-beam induced lattice damage in calcium fluoride crystals
Ning Yu; Michael Nastasi; Kurt E. Sickafus; Kazuhiro Yasuda; Joseph R. Tesmer
Lattice damage in calcium fluoride induced by 360 keV xenon ion irradiation was measured in situ using Rutherford backscattering and channeling (RBS\\/C) techniques. Calcium fluoride single crystals of (100) orientation were irradiated at ? 115 and 35°C by Xe ion beams along a random direction 15° off the (100) axis. A 2 MeV He ion-beam from a 3 MV tandem
Displacement Damage Evolution in GaAs Following Electron, Proton and Silicon Ion Irradiation
Jeffrey H. Warner; Scott R. Messenger; Robert J. Walters; Geoffrey P. Summers; Manuel J. Romero; Edward A. Burke
We characterize radiation induced defects in n-type GaAs following electron, proton, and silicon ion irradiations using deep level transient spectroscopy (DLTS) and electron beam induced current (EBIC) measurements. EBIC micrographs show the existence of radiation induced recombination centers following high energy proton (E MeV) or 22 MeV silicon ion irradiations, which were not observed following 1 MeV electron or 2
Effect of Swift heavy ion irradiation on Tris(8-hydroxyquinoline) aluminum thin films
K. Thangaraju; D. Kanjilal; J. Kumar
Tris-(8-hydroxyquinoline)aluminum (Alq3) is the most widely used light-emitting and electron transport materials in organic electroluminescent (EL) devices to date. Alq3 thin films have been deposited on glass substrates by thermal evaporation process. The deposited Alq3 thin films have been irradiated with Swift heavy ion (SHI) of Li3+ 40 MeV with various ion fluences. The effect of SHI irradiation on Alq3
Microstructure evolution and degradation mechanisms of reactor internal steel irradiated with heavy ions
O. V. Borodin; V. V. Bryk; A. S. Kalchenko; A. A. Parkhomenko; B. A. Shilyaev; G. D. Tolstolutskaya; V. N. Voyevodin
Structure evolution and degradation mechanisms during irradiation of 18Cr–10Ni–Ti steel (material of VVER-1000 reactor internals are investigated). Using accelerator irradiations with Cr3+ and Ar+ ions allowed studying effects of dose rate, different initial structure state and implanted ions on features of structure evolution and main mechanisms of degradation including low temperature swelling and embrittlement of the 18Cr–10Ni–Ti steel. It is
Biophysical characteristics of HIMAC clinical irradiation system for heavy-ion radiation therapy
Tatsuaki Kanai; Masahiro Endo; Shinichi Minohara; Nobuyuki Miyahara; Hiroko Koyama-ito; Hiromi Tomura; Naruhiro Matsufuji; Yasuyuki Futami; Akifumi Fukumura; Takeshi Hiraoka; Yoshiya Furusawa; Koichi Ando; Masao Suzuki; Fuminori Soga; Kiyomitsu Kawachi
Purpose: The irradiation system and biophysical characteristics of carbon beams are examined regarding radiation therapy.Methods and Materials: An irradiation system was developed for heavy-ion radiotherapy. Wobbler magnets and a scatterer were used for flattening the radiation field. A patient-positioning system using X ray and image intensifiers was also installed in the irradiation system. The depth-dose distributions of the carbon beams
Investigation of damage in GaAs single crystals after irradiation by Ne+ ions
A. Zolotaryov; K. Shcherbachev; F. Wu; R. L. Johnson
According to established ideas, the irradiation by energetic ions induces a significant number of point defects (1). This process is multi-stage and includes generation of radiation induced vacancies and interstitial atoms (Frenkel pairs). The subsequent motion of these defects towards the surface and internal interfaces, as well as their interaction with each other, and with other imperfections of an irradiated
Application of ion beam irradiated ePTFE to repair small vessel injuries
NASA Astrophysics Data System (ADS)
Takahashi, N.; Suzuki, Y.; Ujiie, H.; Hori, T.; Iwaki, M.; Yamada, T.
In surgery, bleeding from small injured vessels often requires prompt hemostasis without occlusion. This study evaluated the usefulness of 0.06 mm thick ion beam irradiated ePTFE sheets to repair small holes in vessels. Both surfaces of ePTFE sheets were irradiated with a 150 keV-Ar+ beam with fluences of 5 × 1014 ions/cm2. A small hole up to 2 mm in diameter was created in the common carotid artery of a rabbit. The defect was wrapped with an ion beam irradiated or non-irradiated ePTFE sheet. Fibrin glue was used to fix the ePTFE sheets to the common carotid artery. Hemostasis was instantly obtained with ion beam irradiated ePTFE but was rather difficult when using a non-irradiated ePTFE sheet. Three weeks after implantation, no occlusion was observed. Histological examination showed that the ePTFE sheets functioned as a scaffold for vessel wall regeneration. Thin ion beam irradiated ePTFE would be useful in vascular surgery.
Oxide shell reduction and magnetic property changes in core-shell Fe nanoclusters under ion irradiation
Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You, E-mail: firstname.lastname@example.com [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States); Jiang, Weilin [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States); McCloy, John S. [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164 (United States)
Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe{sub 3}O{sub 4}/Fe{sub 3}N. These NC films were deposited on Si substrates to thickness of ?0.5 ?m using a NC deposition system. The films were irradiated at room temperature with 5.5?MeV Si{sup 2+} ions to ion fluences of 10{sup 15} and 10{sup 16} ions/cm{sup 2}. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization or growth of Fe{sub 3}N. The film retained its Fe-core and its ferromagnetic properties after irradiation. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe{sub 3}O{sub 4} and FeO?+?Fe{sub 3}N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.
Dielectric and transport properties of magnetic insulators irradiated with GeV heavy ions
NASA Astrophysics Data System (ADS)
Costantini, J. M.; Salvetat, J. P.; Brisard, F.
The dielectric and ac/dc transport properties of single crystals of yttrium iron garnet (Y3Fe5O12 and Y3Fe5O12:Si), and barium hexaferrite (BaFe12O19 and BaFe12O1 9:Co,Ti) were investigated after irradiations with Xe and Pb ions in the GeV range. In the virgin n-type samples (Y3Fe5O12:Si and BaFe12O19:Co,Ti), the strong dielectric relaxation below 100 kHz is found to correspond to a space-charge polarization at the blocking metal/insulator contacts yielding a nonohmic dc conductivity. The relaxation frequency decreases with increasing amorphization yield in relation to the decrease of the insulators bulk dc conductivity which becomes ohmic in the amorphous phases. The ac conductivity data of both crystalline and amorphous Y3Fe5O12:Si above 100 kHz and for 100 K
Ion-irradiation of complex hydrocarbons: implications for small Solar System bodies
NASA Astrophysics Data System (ADS)
Moroz, L.; Baratta, G.; Distefano, E.; Strazzulla, G.; Dotto, E.; Barucci, M.; Arnold, G.
Trans-Neptunian Objects (TNOs) and cometary nuclei show remarkable color variations. In the visual and near-infrared spectral regions their colors may range from red to gray or bluish. This probably indicates that surface alteration processes such as space weathering and impact resurfacing plays an essential role in the color diversity of such bodies. In particular, some previous laboratory ion-irradiation experiments demonstrated a transformation of surface colors of ices from gray to red and further to gray. Additional possibility is a transformation of originally red dark refractory organic surface components into a gray carbonized material as a result of ion irradiation. We simulated such an "ageing" effect by an irradiation of a natural dark red organic samples (asphaltite and kerite). The samples were irradiated by 30-60 keV H+, N+ and Ar++ ions and their reflectance spectra were measured before and after irradiation. The results indicate that initially red spectra of organics progressively flatten with increasing ion fluences. The laboratory spectra have been compared with astronomical spectra of TNOs. We demonstrate that an observed variety of TNO' spectral slopes can be reproduced by our laboratory spectra corresponding to different ion fluences. If we assume that fresh surfaces of some TNOs are red due to their refractory organic components, then their irradiation by ion populations in the Solar System in combination with collisional evolution exposing these fresh surfaces could have produced a variety of colors.
Structural and morphological properties of Ag ion irradiated SnO2 thin films
NASA Astrophysics Data System (ADS)
Abhirami, K. M.; Matheswaran, P.; Gokul, B.; Sathyamoorthy, R.; Asokan, K.
SnO2 thin films of thickness 300 nm were prepared by reactive thermal evaporation and subjected to sintering at 600 °C for 2 hr. The annealed films were irradiated using silver (Ag) ions with energy of 120 MeV at different fluences (1×1011, 5×1011, 1×1012, 5×1012 and 1×1013 ions/cm2). The effect of swift heavy ion (SHI) irradiation on structural, morphological and optical properties were studied using X-ray diffractometer (XRD), Scanning electron microscopy (SEM) and UV-visible spectrophotometer. XRD studies showed formation of tin oxide with tetragonal structure. Morphology analysis revealed uniform deposition of the material with increase in grain size after irradiation upto 1×1012 ions/cm2 and beyond that size tends to decrease. In addition, agglomeration of nanocrystalline grains was observed after Ag ion bombardment with varying fluence. The transmittance decreases from 90% to 80% as the fluence increases.
In situ measurement of surface potential developed on MgO thin film surface under ion irradiation using ion scattering spectroscopy
T. Nagatomi; T. Kuwayama; K. Yoshino; Y. Takai; Y. Morita; M. Nishitani; M. Kitagawa
The application of ion scattering spectroscopy (ISS) to the in situ measurement of the surface potential developed on an insulator surface under positive ion irradiation was investigated. The ISS spectra measured for a MgO film of 600 nm thickness on a Si substrate by the irradiation of 950 eV He+ ions revealed that the surface is positively charged by approximately
Modifying the morphology and magnetic properties of magnetite nanoparticles using swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Gokhale, Shubha; Lamba, Subhalakshmi; Kumari, Neha; Singh, Bhupendra; Avasthi, D. K.; Kulkarni, S. K.
Magnetite (Fe3O4) nanospheres of ˜8-11 nm diameter synthesized using a chemical co-precipitation method were deposited as thin films on different substrates using spin coating. The thin films were irradiated with Ag ions at 100 MeV energy. Comparison of unirradiated, as synthesized Fe3O4 nanoparticulate thin film and ion irradiated film shows that irradiation causes dramatic changes in the morphology, structure and magnetic properties. Monte Carlo simulations carried out on this system indicate that the origin of the changes in the magnetic properties lies in the enhanced magnetic anisotropy energy density and reorientation of magnetic easy axis.
The effect of composition on the formation of light-emitting Si nanostructures in SiO{sub x} layers on irradiation with swift heavy ions
Kachurin, G. A., E-mail: firstname.lastname@example.com; Cherkova, S. G.; Marin, D. V.; Kesler, V. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Skuratov, V. A. [Joint Institute for Nuclear Research (Russian Federation); Cherkov, A. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)
The SiO{sub x} layers different in composition (0 < x < 2) are irradiated with Xe ions with the energy 167 MeV and the dose 10{sup 14} cm{sup -2} to stimulate the formation of light-emitting Si nanostructures. The irradiation gives rise to a photoluminescence band with the parameters dependent on x. As the Si content is increased, the photoluminescence is first enhanced, with the peak remaining arranged near the wavelength {lambda} Almost-Equal-To 600 nm, and then the peak shifts to {lambda} Almost-Equal-To 800 nm. It is concluded that the emission sources are quantum-confined nanoprecipitates formed by disproportionation of SiO{sub x} in ion tracks due to profound ionization losses. Changes in the photoluminescence spectrum with increasing x are attributed firstly to the increase in the probability of formation of nanoprecipitates and then to the increase in their dimensions; the latter effect is accompanied with a shift of the emission band to longer wavelengths. The subsequent quenching of photoluminescence is interpreted as a result of the removal of quantum confinement in nanoprecipitates and their coagulation.
Anomalous charge loss from floating-gate memory cells due to heavy ions irradiation
G. Cellere; A. Paccagnella; L. Larcher; A. Chimenton; J. Wyss; A. Candelori; A. Modelli
We are presenting new data on the charge loss in large floating gate (FG) memory arrays subjected to heavy ion irradiation. Existing models for charge loss from charged FG and generation-recombination after a heavy ion strike are insufficient to justify (or in contrast with) our experimental results. In particular, the charge loss is by far larger than predicted by existing
Studies on PAN-based carbon fibers irradiated by Ar+ ion beams.
Park, Soo-Jin; Seo, Min-Kang; Kim, Hak-Yong; Lee, Douk-Rae
In this work, the effects of Ar+ ion beam irradiation on carbon fibers were studied using tensile and surface analytical techniques. The single-fiber pull-out test was executed in order to characterize the fiber/epoxy matrix interfacial adhesion. The Ar+ ion beam was irradiated using an ion-assisted reaction (IAR) method in reactive gas conditions under an oxygen environment with 1 x 10(16) ions/cm(2) Ar+ ion dose (ID), 6 sccm blown gas flow rate, and different ion beam energy intensities. From the experimental results, both the interfacial shear strength (IFSS) and fracture toughness (Gi) were found to increase with increasing Ar+ ion irradiation intensity. This was probably due to the fact that Ar+ ion beam irradiation on carbon fibers was effective in altering their surface physical chemistry and structural morphology, resulting in improved interfacial adhesion in the fiber/epoxy matrix. The reliability of single-fiber pull-out test data could be improved by statistical analysis using the Weibull distribution, which served to predict the variation of the mechanical interfacial properties in a composite system. PMID:16256547
Effect of Proton and Silicon Ion Irradiation on Defect Formation in GaAs
Jeffrey H. Warner; Christophe Inguimbert; Mark E. Twigg; Scott R. Messenger; Robert J. Walters; Manuel J. Romero; Geoffrey P. Summers
Electrical and structural changes in GaAs are monitored using electron beam induced current (EBIC) and transmission electron microscopy (TEM) measurements after irradiation by protons and silicon ions. It has been determined that higher energy protons (E ges 10 MeV) and silicon ions disordered regions that are electrically and structurally different than those produced by lower energy protons. The data suggest
Nano-embossed structure on polypropylene induced by low energy Ar ion beam irradiation
Kim, Ho-Young
Nano-embossed structure on polypropylene induced by low energy Ar ion beam irradiation Sk. Faruque: Polypropylene Ar ion beam Nanostructure Hardness The surface morphology evolution of polypropylene (PP on the wettability, surface chemistry and surface morphology of polymers, especially polypropylene, were studied [6
Carbon nanotube's modification by focused ion beam irradiation and its healing strategies
NASA Astrophysics Data System (ADS)
Xu, Zongwei; Xu, Lihua; Fang, Fengzhou; Gao, Haifeng; Li, Wanli
Single-walled carbon nanotube (SWNT) clusters' properties and performance have been studied after irradiated by focused ion beam (FIB) Ga ions and post annealing recovery methods. The SWNT was irradiated by FIB with different energy and different doses ranging from 1013 to 1017 ions/cm2. Raman spectroscopy results showed that FIB with larger energy or larger ion dose would cause distinct SWNT structure defects. It was also found that scanning electron microscope (SEM) observations would slightly affect the SWNT's Raman results by electron beam induced carbon deposition. Resulting from the unique reconstruction ability of carbon nanotube's (CNT's) network structures, the SWNT's ion-induced defects can be effectively healed by the post heat annealing from 300 °C to 600 °C for the ion dose less than 1016 ions/cm2. And laser irradiation annealing method also studied to heal the defects in SWNT with 25 mW laser power. Research results would be beneficial for the optimization of the carbon nanotube devices' functionalizations using FIB Ga ions irradiation.
Oxide Shell Reduction and Magnetic Property Changes in Core-Shell Fe Nanoclusters under Ion Irradiation
Sundararajan, Jennifer A.; Kaur, Maninder; Jiang, Weilin; McCloy, John S.; Qiang, You
Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe3O4/FeO. These NC films were were deposited on Si substrates to thickness of ~0.5 micrometers using a NC deposition system. The films were irradiated at room temperature with 5.5 MeV Si2+ ions to ion fluences of 1015 and 1016 ions/cm2. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization of Fe3N. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe3O4 and FeO+Fe3N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.
Influence of irradiation spectrum and implanted ions on the amorphization of ceramics
Zinkle, S.J.; Snead, L.L.
Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe{sup 2+} ions at RT produced amorphization in the implanted ion region after damage levels of {similar_to}1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He{sup +} ions at RT. By comparison with published results, it is concluded that the implantation of certain chemical species has a pronounced effect on the amorphization threshold dose of all five materials. Intense ionizing radiation inhibits amorphization in Si3N4, but does not appear to significantly influence the amorphization of SiC.
Grain growth and crack formation in NiO thin films by swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Mallick, P.; Biswal, R.; Rath, Chandana; Agarwal, D. C.; Tripathi, A.; Avasthi, D. K.; Kanjilal, D.; Satyam, P. V.; Mishra, N. C.
NiO thin films grown on Si(1 0 0) substrates by electron beam evaporation and sintered at 700 °C, were irradiated by 120 MeV Au 9+ ions. Though irradiation is known to induce lattice disorder and suppression of crystallinity, we observe grain growth at some fluences of irradiation. Associated with the growth of grains, the films develop cracks at a fluence of 3 × 10 12 ions cm -2. The width of the cracks increased at higher fluences. Swift heavy ion irradiation induced atomic diffusion and strain relaxation in nanoparticle thin films, which are not in thermodynamic equilibrium, seem to be responsible for the observed grain growth. This phenomenon along with the tensile stress induced surface instability lead to crack formation in the NiO thin films.
Effect of swift heavy ion irradiation on ethylene-chlorotrifluoroethylene copolymer
NASA Astrophysics Data System (ADS)
Singh, Lakhwant; Devgan, Kusum; Samra, Kawaljeet Singh
The swift heavy irradiation induced changes taking place in ethylene-chlorotrifluoroethylene (E-CTFE) copolymer films were investigated in correlation with the applied doses. Samples were irradiated in vacuum at room temperature by lithium (50 MeV), carbon (85 MeV), nickel (120 MeV) and silver (120 MeV) ions with the fluence in the range of 1×1011-3×1012 ions cm-2. Structural and thermal properties of the irradiated as well as pristine E-CTFE films were studied using FTIR, UV-visible, TGA, DSC and XRD techniques. Swift heavy ion irradiation was found to induce changes in E-CTFE depending upon the applied doses.
Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect
NASA Astrophysics Data System (ADS)
Khodja, H.
Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.
Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation
Zhang Yanwen; Jiang Weilin; Wang Chongmin; Edmondson, Philip D.; Zhu Zihua; Gao Fei [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States); Namavar, Fereydoon [University of Nebraska Medical Center, Omaha, Nebraska 68198 (United States); Lian Jie [Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Weber, William J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Grain growth, oxygen stoichiometry, and phase stability of nanostructurally stabilized cubic zirconia (NSZ) are investigated under 2 MeV Au-ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with irradiation dose to {approx}30 nm at {approx}35 dpa. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that the grain growth is not thermally activated and irradiation-induced grain growth is the dominating mechanism. While the cubic structure is retained and no new phases are identified after the high-dose irradiations, oxygen reduction in the irradiated NSZ films is detected. The ratio of O to Zr decreases from {approx}2.0 for the as-deposited films to {approx}1.65 after irradiation to {approx}35 dpa. The loss of oxygen suggests a significant increase in oxygen vacancies in nanocrystalline zirconia under ion irradiation. The oxygen deficiency may be essential in stabilizing the cubic phase to larger grain sizes.
Microstructural development in a model austenitic alloy following electron and ion irradiation
NASA Astrophysics Data System (ADS)
Sakaguchi, N.; Kinoshita, H.; Watanabe, S.; Sueishi, Y.; Akasaka, N.; Takahashi, H.
In order to study the microstructural evolution of cascade and interaction between cascade and He, the irradiations were carried out using ion accelerator to introduce the cascade and a high resolution high voltage electron microscope (1250 kV) to irradiate with electrons and for in situ observation. A lot of small cascades were introduced by Ni +-ion irradiation at room temperature, and due to following electron irradiation at higher temperature interstitial type dislocation loops were nucleated from the interstitials rich zone and grew. On the other hand the cascades transferred to SFTs during annealing above 623 K. When He atoms were previously implanted, He bubbles were formed at cascades. Also segregation of solutes and precipitates were induced at cascades during electron irradiation.
Effect of Ar+ ion irradiation on the microstructure of pyrolytic carbon
NASA Astrophysics Data System (ADS)
Feng, Shanglei; Yang, Yingguo; Li, Li; Zhang, Dongsheng; Yang, Xinmei; Bai, Shuo; Xia, Huihao; Yan, Long; Huai, Ping; Zhou, Xingtai
Pyrolytic carbon (PyC) coatings prepared by chemical vapor deposition were irradiated by 300 keV Ar+ ions. Then, atomic force microscopy, synchrotron-based grazing incidence X-ray diffraction, Raman spectroscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were employed to study how Ar+ irradiation affects the microstructure of PyC, including the microstructural damage mechanisms and physics driving these phenomena. The 300 keV Ar+ ion irradiation deteriorated the structure along the c-axis, which increased the interlayer spacing between graphene layers. With increasing irradiation dose, the density of defect states on the surface of PyC coating increases, and the basal planes gradually loses their initial ordering resulting in breaks in the lattice and turbulence at the peak damage dose reaches 1.58 displacement per atom (dpa). Surprisingly, the PyC becomes more textured as it becomes richer in structural defects with increasing irradiation dose.
Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)
NASA Astrophysics Data System (ADS)
Gowa, Tomoko; Shiotsu, Tomoyuki; Urakawa, Tatsuya; Oka, Toshitaka; Murakami, Takeshi; Oshima, Akihiro; Hama, Yoshimasa; Washio, Masakazu
High linear energy transfer (LET) heavy ion beams were used to irradiate poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth were precisely evaluated by analyzing each of the films of the irradiated samples, which were made of stacked ETFE films. It was indicated that conjugated double bonds were generated by heavy ion beam irradiation, and their amounts showed the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for samples irradiated in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.
Amorphization of oxides in ODS materials under low and high energy ion irradiations
NASA Astrophysics Data System (ADS)
Lescoat, M.-L.; Monnet, I.; Ribis, J.; Dubuisson, P.; de Carlan, Y.; Costantini, J.-M.; Malaplate, J.
Oxide Dispersion Strengthened (ODS) ferritic/martensitic (F/M) steels are promising materials as structural components for fusion reactors. Their excellent creep properties are provided by the nano-dispersed oxides reinforcing the material. This oxide dispersion has to be as stable as possible under irradiation at high temperatures. In the present work, low and high energy ion irradiation experiments were used to investigate microstructural stability under irradiation of oxides. Two iron base ODS alloys were studied: the ODS DY reinforced by yttrium and titanium oxides and the ODS EM10 reinforced by magnesium oxides. TEM investigations of the crystallinity for large oxides ( d ? 50 nm) after irradiations reveal that, in both alloys, amorphization can occur due to electronic excitations or ballistic damages. Amorphization appears to depend on the nature of the oxides. Low energy ion irradiation results show that a critical temperature and a critical dose may exist, for which no amorphization is observed.
Enhancement of the field emission of carbon nanotubes straightened by application of argon ion irradiation
NASA Astrophysics Data System (ADS)
Kim, Do-Hyung; Jang, Hoon-Sik; Kim, Chang-Duk; Cho, Dong-Soo; Kang, Hee-Dong; Lee, Hyeong-Rag
The field emission properties of carbon nanotubes (CNTs) were enhanced by argon ion irradiation. Argon irradiation treatment led to an enhancement in the emission properties of CNTs which showed a decrease in turn-on field and an increase in total emission current after the treatment. The irradiation treatment permanently straightened as-grown curly CNTs, and, as a result, the local electric field was increased, due to the increased aspect ratio and reduced mutual shield effect. In addition, increased defects, produced by the argon irradiation are likely to make their effective surfaces more active, thus emitting more electrons.
Enhancement of impact-induced mechanoluminescence by swift heavy ion irradiation
Zhan, T. Z.; Terasawa, Y. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Xu, C. N. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); National Institute of Advanced Industrial Science and Technology, Kyushu, 807-1 Shuku, Tosu, Saga 841-0052 (Japan); CREST, Japan Science and Technology Agency, 4 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Yamada, H. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); National Institute of Advanced Industrial Science and Technology, Kyushu, 807-1 Shuku, Tosu, Saga 841-0052 (Japan); Zhang, L. [National Institute of Advanced Industrial Science and Technology, Kyushu, 807-1 Shuku, Tosu, Saga 841-0052 (Japan); Iwase, H.; Kawai, M. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
In this Letter, we report a strategy using swift heavy ion (SHI) irradiation to enhance the impact-induced mechanoluminescence (ML) in ML materials. The impact-induced ML intensity of CaSrAl{sub 2}Si{sub 2}O{sub 8}:Eu{sup 2+} was enhanced by about one order of magnitude by using SHI irradiation. Furthermore, the enhancement was found to depend on electronic stopping power and irradiation fluence. The density of traps of a type suitable for impact-induced ML is considered to be increased by the SHI irradiation, resulting in the impact-induced ML enhancement.
Ion-irradiation-induced densification of zirconia sol-gel thin films
Levine, T.E.; Giannelis, E.P. [Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering; Kodali, P.; Tesmer, J.; Nastasi, M. [Los Alamos National Lab., NM (United States); Mayer, J.W. [Arizona State Univ., Tempe, AZ (United States)
We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.
Cluster size dependence of sputtering yield by cluster ion beam irradiation
NASA Astrophysics Data System (ADS)
Seki, T.; Murase, T.; Matsuo, J.
In order to investigate the dependence of the sputtering yield on cluster size, surfaces were irradiated with cluster ion beams with various size distributions, and the sputtering yields were measured. It was found that there was a threshold energy for sputtering with cluster ion irradiation. When the cluster size was constant, the sputtering yield was proportional to acceleration energy. These results suggested an empirical formula to calculate sputtering yield from the ion energy and the size distribution of the cluster. The empirical formula indicates that the sputtering yield is proportional to the 1.1 power of the size, when the acceleration energy per atom is constant.
Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma
Higo, Morihiro [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Uzawa, Katsuhiro [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan) and Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, Chiba (Japan)]. E-mail: firstname.lastname@example.com; Kawata, Tetsuya [Department of Radiology, Graduate School of Medicine, Chiba University, Chiba (Japan); Kato, Yoshikuni [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Kouzu, Yukinao [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Yamamoto, Nobuharu [Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, Chiba (Japan); Shibahara, Takahiko [Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, Chiba (Japan); Mizoe, Jun-etsu [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hisao [Department of Radiology, Graduate School of Medicine, Chiba University, Chiba (Japan); Tsujii, Hirohiko [Center of Excellence (COE) Program in the 21st Century, Graduate School of Medicine, Chiba University, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Tanzawa, Hideki [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, Chiba (Japan); Center of Excellence (COE) Program in the 21st Century, Graduate School of Medicine, Chiba University, Chiba (Japan)
Purpose The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. Methods and Materials Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. Results We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. Conclusions Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.
Pattern-induced magnetic anisotropy in FePt thin films by ion irradiation
Jaafar, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Dpto. Fisica de la Materia Condensada, UAM, ES-28049 Madrid (Spain); Sanz, R. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Nanoate SL, Poeta Rafael Morales 2, ES-28702 San Sebastian de los Reyes, Madrid (Spain); McCord, J. [Institute of Ion Beam Physics and Materials Research, FZD, D-01314 Dresden (Germany); Jensen, J. [Thin Film Physics, Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Schaefer, R. [Leibniz Institute for Solid State and Materials Research, IFW, Helmholtzstrasse 20, D-01069 Dresden (Germany); Vazquez, M.; Asenjo, A. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain)
The magnetic properties of FePt thin films have been modified by exposing the samples to irradiation of 4 MeV Cl{sup 2+} ions. Patterned magnetic films, without modified topographical profile, were fabricated by irradiating the films through a shadowing micrometric mask. The structural changes, ascribed to the ion-beam-induced amorphization of the thin films, promote the modification of the magnetic anisotropy. In particular, the out-of-plane component of the magnetization decreases simultaneously with an enhancement of in-plane anisotropy by increasing ion fluence. Moreover, the nonirradiated regions present unexpected anisotropic behavior owing to the stray field of the irradiated regions. The control of this effect, which can have unwished consequences for the patterning of magnetic properties by ion bombardment, needs to be suitably addressed.
Etch-free formation of porous silicon by high-energy ion irradiation
Perez-Bergquist, Dr. Alejandro G. [Los Alamos National Laboratory (LANL); Naab, Fabian U. [University of Michigan; Zhang, Yanwen [ORNL; Wang, Prof. Lumin [University of Michigan
In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650 C. Extremely high ion fluences of at least 2 1018 ions/cm2 were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.
1\\/f noise studies of swift heavy ion irradiated magnetite thin films
M. Wasi Khan; Ravi Kumar; J. P. Srivastava; S. K. Arora; R. J. Choudhary; I. V. Shvets
The effect of 190 MeV 107Ag ion irradiation on antiphase boundaries (APBs) of epitaxial Fe3O4 thin films (thickness ˜70 nm) grown on MgO (1 0 0) oriented substrate has been investigated. The X-ray diffraction shows that at low fluence values upto 5 × 1011 ions\\/cm2, the strain in the films is relaxed whereas at high fluence 1 × 1012 ions\\/cm2,
Effect of helium on swelling and microstructural evolution in ion-irradiated V-15Cr5Ti alloy*1
B. A. Loomis; B. J. Kestel; S. B. Gerber; G. Ayrault
An investigation was made on the effects of implanted helium on the swelling and microstructural evolution that results from energetic single- and dual-ion irradiation of the V-15Cr-5Ti alloy. Single-ion irradiations were utilized for a simulated production of the irradiation damage that might be expected from neutron irradiation of the alloy in a reactor with a fast neutron energy spectrum (E
Effect of ion beam irradiation on magnetism of Fe(100) outermost surfaces studied by spin-polarized ion scattering spectroscopy
T. T. Suzuki; H. Kuwahara; Y. Yamauch
We study the effect of 2keV Ar+ ion beam irradiation (IBI) on the outermost surface magnetism of an Fe(100) film by spin-polarized ion scattering spectroscopy (SP-ISS). We found that the coercivity of the outermost surface is enhanced with IBI. On the other hand, spin polarization is independent of IBI. These effects of IBI on surface magnetism are discussed in terms
In-situ Fe+ Ion Irradiation of an Oxide Dispersion Strengthened Steel
NASA Astrophysics Data System (ADS)
de Castro, V.; Briceno, M.; Jenkins, M. L.; Kirk, M.; Lozano-Perez, S.; Roberts, S. G.
Oxide Dispersion Strengthened (ODS) reduced activation ferritic steels are promising candidate materials for structural components of both nuclear fission and fusion reactors. However, when irradiated with energetic particles, they may suffer changes on their microstructures that degrade their mechanical performance. In-situ transmission electron microscopy studies on ion-irradiated ODS steels can give remarkable insights into fundamental aspects of radiation damage allowing dynamic observations of defect formation, mobilities, and interactions during irradiation. In this investigation, a commercially available PM2000 ODS steel was in-situ irradiated with 150 KeV Fe+ at room temperature and 700°C. These experiments showed that the oxide nanoparticles in these steels remain stable up to the higher irradiation dose (~ 1.5 dpa), and that these particles seem to be effective sinks for irradiation induced defects.
Enhanced electron field emission from carbon nanotubes irradiated by energetic C ions.
Sun, Peng-Cheng; Deng, Jian-Hua; Cheng, Guo-An; Zheng, Rui-Ting; Ping, Zhao-Xia
The field emission performance and structure of the vertically aligned multi-walled carbon nanotube arrays irradiated by energetic C ion with average energy of 40 keV have been investigated. During energetic C ion irradiation, the curves of emission current density versus the applied field of samples shift firstly to low applied fields when the irradiation doses are less than 9.6 x 10(16) cm(-2), and further increase of dose makes the curves reversing to a high applied field, which shows that high dose irradiation in carbon nanotube arrays makes their field emission performance worse. After energetic ion irradiation with a dose of 9.6 x 1016 cm(-2), the turn-on electric field and the threshold electric field of samples decreased from 0.80 and 1.13 V/microm to 0.67 and 0.98 V/microm respectively. Structural analysis of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy indicates that the amorphous carbon nanowire/carbon nanotube hetero nano-structures have been fabricated in the C ion irradiated carbon nanotubes. The enhancement of electron field emission is due to the formation of amorphous carbon nanowires at the tip of carbon nanotube arrays, which is an electron emitting material with low work function. PMID:22962775
Grain Growth and Phase Stability of Nanocrystalline Cubic Zirconia under Ion Irradiation
Zhang, Yanwen [ORNL; Jiang, Weilin [Pacific Northwest National Laboratory (PNNL); Wang, Chongmin [Pacific Northwest National Laboratory (PNNL); Namavar, Fereydoon [University of Nebraska Medical Center; Edmondson, Philip D. [Pacific Northwest National Laboratory (PNNL); Zhu, Zihua [Pacific Northwest National Laboratory (PNNL); Gao, Fei [Pacific Northwest National Laboratory (PNNL); Lian, Jie [Rensselaer Polytechnic Institute (RPI); Weber, William J [ORNL
Grain growth, oxygen stoichiometry and phase stability of nanostructurally-stabilized cubic zirconia (NSZ) are investigated under 2 MeV Au ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with dose, and follows a power law (n=6) to a saturation value of ~30 nm that decreases with temperature. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that the grain growth is not thermally activated and irradiation-induced grain growth is the dominating mechanism. While the cubic structure is retained and no new phases are identified after the high-dose irradiations, oxygen reduction in the irradiated NSZ films is detected. The ratio of O to Zr decreases from ~2.0 for the as-deposited films to ~1.65 after irradiation to ~35 dpa. The loss of oxygen suggests a significant increase of oxygen vacancies in nanocrystalline zirconia under ion irradiation. The oxygen deficiency may be essential in stabilizing the cubic phase to larger grain sizes.
Nanocrystallization of Pure Titanium Surface by Intense Pulsed Ion Beam Irradiation
NASA Astrophysics Data System (ADS)
Akamatsu, Hiroshi; Azuma, Kingo; Fujiwara, Etsuo; Yatsuzuka, Mitsuyasu
A hydrogen intense pulsed ion beam (IPIB) with an ion energy of 180 keV, ion current density of 460 A/cm2, and pulse duration of 65 ns was irradiated on a pure titanium surface. A rapid heating and cooling treatment due to irradiation of the IPIB led to the formation of a nanocrystalline structure with the average grain size of 32 nm. The reduction in grain size resulted in the improvement of hardness and tribological property of the sample. The IPIB-irradiated Ti is 1.3 times harder than the non-irradiated one. The friction coefficient of pure Ti was reduced from 0.6 to 0.1 by IPIB-irradiation, and the IPIB-irradiated Ti maintained the low friction coefficient till 200 wear cycles. The calculated cooling rate of the IPIB-irradiated Ti, 3.0 × 107 K/s in the present experiment, is sufficiently high to form a nanocrystalline structure.
Dynamical response of helium bubble motion to irradiation with high-energy self-ions in aluminum at high temperature.
Ono, K.; Miyamoto, M.; Arakawa, K.; Birtcher, R. C.; Materials Science Division; Shimane Univ.; Osaka Univ.
Brownian-type motion of helium bubbles in aluminum and its dynamical response to irradiation with 100-keV Al{sup +} ions at high temperatures has been studied using in situ irradiation and transmission electron microscopy. It is found that, for most bubbles, the Brownian-type motion is retarded under irradiation, while the mobility returns when the irradiation is stopped. In contrast, under irradiation, a small number of bubbles display exceptionally rapid motion associated with the change in bubble size. These effects are discussed in terms of the dynamical interaction of helium bubbles with cascade damage formed by the high-energy self-ion irradiation.
Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation*
Ling, Anna Pick Kiong; Ung, Ying Chian; Hussein, Sobri; Harun, Abdul Rahim; Tanaka, Atsushi; Yoshihiro, Hase
Objective: Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation. Methods: In this study, the dry seeds of O. sativa were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, followed by in-vitro germination under controlled conditions. Morphological and biochemical studies were conducted to investigate the morphological and physiological responses of O. sativa towards ion beam irradiation. Results: The study demonstrated that low doses (10 Gy) of ion beam have a stimulating effect on the height, root length, and fresh weight of the plantlets but not on the number of leaves. Meanwhile, doses higher than 10 Gy caused reductions in all the morphological parameters studied as compared to the control samples. The highest total soluble protein content [(2.11±0.47) mg/g FW] was observed in plantlets irradiated at 20 Gy. All irradiated plantlets were found to have 0.85% to 58.32% higher specific activity of peroxidase as compared to the control samples. The present study also revealed that low doses of ion beam (10 and 20 Gy) had negligible effect on the total chlorophyll content of O. sativa plantlets while 40 Gy had a stimulating effect on the chlorophyll content. Plantlets irradiated between 40 to 120 Gy were shown to be 0.38% to 9.98% higher in total soluble nitrogen content which, however, was not significantly different from the control samples. Conclusions: Carbon ion beam irradiation administered at low to moderate doses of 10 to 40 Gy may induce O. sativa mutants with superior characteristics. PMID:24302713
Effect of irradiation parameters on defect aggregation during thermal annealing of LiF irradiated with swift ions and electrons
NASA Astrophysics Data System (ADS)
Schwartz, K.; Volkov, A. E.; Sorokin, M. V.; Neumann, R.; Trautmann, C.
Absorption spectroscopy were performed to study the effects of thermal annealing on the aggregation of color centers in LiF crystals irradiated with different ions between carbon and uranium of megaelectron volt-gigaelectron volt energy. The beam parameters such as energy, energy loss, and fluence have a pronounced influence on the initial defect composition and concentration as well as their evolution upon thermal annealing. A distinct phenomenon was observed, viz., the enhancement of Fn centers for annealing temperatures between 500 and 700 K, followed by Li colloid formation above 700 K. The phenomenon requires specific irradiation conditions whereas the formation of Mg colloids from Mg impurities occurs in all irradiated crystals. The mechanisms of annealing and colloid formation are discussed.
Ultraviolet Photolysis Studies on XeO4 in Noble-Gas and F2 Matrices and the Formation and Characterization of a New Xe(VIII) Oxide, (?(2) -O2 )XeO3.
Vent-Schmidt, Thomas; Goettel, James T; Schrobilgen, Gary J; Riedel, Sebastian
The photolytic behavior of the thermochemically unstable xenon(VIII) oxide XeO4 was investigated by UV irradiation in noble-gas and F2 matrices. Photolysis of Xe(16) O4 or Xe(18) O4 in noble-gas matrices at 365?nm yielded XeO3 and a new xenon(VIII) oxide, namely, (?(2) -O2 )XeO3 , which, along with XeO4 , was characterized by matrix-isolation IR spectroscopy and quantum-chemical calculations. Calculations of the UV spectrum showed that the photodecomposition is induced by an n??* transition, but the nature of the excitation differs when different light sources are used. There is strong evidence for the formation of mobile (1) D excited O atoms in the case of excitation at 365?nm, which led to the formation of (?(2) -O2 )XeO3 by reaction with XeO4 . Matrix-isolation IR spectroscopy in Ne and Ar matrices afforded the natural-abundance xenon isotopic pattern for the ?3 (T2 ) stretching mode of Xe(16) O4 , and (18) O enrichment provided the (16) O/(18) O isotopic shifts of XeO4 and (?(2) -O2 )XeO3 . PMID:26095795
Heavy ion irradiation of U–Mo\\/Al dispersion fuel
N. Wieschalla; A. Bergmaier; P. Böni; K. Böning; G. Dollinger; R. Großmann; W. Petry; A. Röhrmoser; J. Schneider
The usage of high-density U–Mo\\/Al dispersion fuel for high burn up in research and test reactors seems to be limited by the unfavourable interdiffusion layer between the fuel and the Al-matrix, which develops during irradiation. This interdiffusion layer was observed up to now only after costly and time consuming in-pile irradiation and could not be created in out-of-pile experiments. This
Nickel ion irradiation of plasitically deformed martensitic titanium nickel thin films
NASA Astrophysics Data System (ADS)
Lagrange, T.; Schäublin, R.; Grummon, D. S.; Gotthardt, R.
At present, little is known about the response of the martensitic phase in TiNi alloys to heavy ion irradiation. However, previous studies [2, 3] of ion and electron irradiation show that these alloys are highly susceptible to disorder and amorphization at damage levels below 1 dpa. This substantially affects their transformation characteristics and their shape memory effect. The present study focuses on the effect of 5 MeV Ni ion irradiation of plastically strained (\\varepsilonsim 4%) martensitic TiNi thin films, which is used as a processing technique for a novel out of plane bending actuator. Conceptually, the frustration of the martensitic transformation due to ion beam damage in a 2 ?pm surface layer of a 6 ?pm thick film will create a sharp differential latent strain on reverse transformation. This latent strain causes a two-way bending motion during cycling heating and cooling. This processing technique can be used to do useful mechanical work on both heating and cooling. To better understand the behavior of these ion irradiated thin films, TEM observations and motion experiments were conducted. Results are presented and discussed as they relate to the ion induced microstructure and its influence on the martensitic transformation.
Ion beam induced conductivity in chemically vapor deposited diamond films
S. Prawer; A. Hoffman; R. Kalish
Polycrystalline diamond films deposited by the microwave plasma chemical vapor deposition (CVD) technique onto quartz substrates have been irradiated with 100 keV C and 320 keV Xe ions at room temperature and at 200 °C. The dose dependence of the electrical conductivity measured insitu exhibited complicated, nonmonotonic behavior. High doses were found to induce an increase of up to ten
High energy ion irradiation effects on mechanical properties of polymeric materials
NASA Astrophysics Data System (ADS)
Kudoh, H.; Sasuga, T.; Seguchi, T.
The authors prepared ion irradiation system to study irradiation effect on polymer materials, and irradiated carbon/glass fiber reinforced plastic (CFRP, GFRP), polymethylmethacrylate (PMMA), polyethylene (PE), polytetrafluoroethylene (PTFE), and cellulose tri-acetate (CTA), with high energy ions using cyclotron under vacuum at room temperature. Flexural strength in bending test or elongation at break in tensile test decreased with absorbed dose, but the behavior to the dose was the same as that in gamma or 2 MeV electron irradiation. We have found that there is little LET effect for polymers used in terms of change in mechanical properties within the LET range in this work. However, the change in molecular weight for PMMA and optical density for CTA in UV region showed a clear LET dependence above a certain LET, which probably means overlapping between spurs.
Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments
NASA Technical Reports Server (NTRS)
Christoffersen, R.; Keller, L. P.
Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.
Electron capture from H-2 to highly charged Th and Xe ions trapped at center-of-mass energies near 6 eV
Weinberg, G.; Beck, B. R.; Steiger, J.; Church, David A.; McDonald, J.; Schneider, D.
Ions with charge states as high as 80+, produced in the Lawrence Livermore National Laboratory electron beam ion trap were extracted and transferred to a Penning ion trap (RETRAP). RETRAP was operated at cryogenic temperature in the field of a...
Mutation induction in bacteria after heavy ion irradiation
Horneck, G.; Kozubek, S. [Ceskoslovenska Akademie Ved, Brno (Czechoslovakia)
From a compilation of experimental data on the mutagenic effects of heavy ions in bacteria, main conclusions have been drawn as follows: (1) The mutagenic efficacy of heavy ions in bacteria depends on physical and biological variables. Physical variables are the radiation dose, energy and charge of the ion; the biological variables are the bacterial strain, the repair genotype of bacteria, and the endpoint investigated (type of mutation, induction of enzymes related to mutagenesis); (2) The responses on dose or fluence are mainly linear or linear quadratic. The quadratic component, if found for low LET radiation, is gradually reduced with increasing LET; (3) At low values of Z and LET the cross section of mutation induction sigma m (as well as SOS response, sigma sos and lambda phage induction), sigma lambda versus LET curves can be quite consistently described by a common function which increases up to approximately 100 keV/mu m. For higher LET values, the sigma(m) versus LET curves show the so-called `hooks` observed also for other endpoints; (4) For light ions (Z is less than or equal to 4), the cross sections mostly decrease with increasing ion energy, which is probably related to the decrease of the specific energy departed by the ion inside the sensitive volume (cell). For ions in the range of Z = 10, sigma(m) is nearly independent on the ion energy. For heavier ions (Z is greater than or equal to 16), sigma(m) increases with the energy up to a maximum or saturation around 10 MeV/u. The increment becomes steeper with increasing atomic number of the ion. It correlates with the increasing track radius of the heavy ion; (5) The mutagenic efficiency per lethal event changes slightly with ion energy, if Z is small indicating a rough correlation between cellular lethality and mutation induction, only.
Microstructural and Mechanical Property Changes in Ion Irradiated Tunsgten
General, Michael
time and volume allowed is limited by the computing power available. To run a simulation with millions of atoms, super computers are needed. Each individual atom is indexed and calculated during each iterate. This technique is computationally... the differences between of the range, R, and the projected range, Rp. Computer programs, such as, Stopping and Range of Ion in Matter (SRIM) can calculate the Rp of certain ions with a discrete energy into most materials. Figure 2.2: An ion traveling...
Photoabsorption spectrum of the Xe@C60 endohedral fullerene
NASA Astrophysics Data System (ADS)
Chen, Zhifan; Msezane, A. Z.
Photoabsorption spectrum of the Xe@C60 endohedral fullerene has been studied using the time-dependent-density-functional-theory (TDDFT), which represents the dynamical polarizability of an interacting electron system by an off-diagonal matrix element of the resolvent of the Liouvillian superoperator and solves the problem with the Lanczos algorithm. The method has been tested with the photoabsorption spectra for the free Xe atom and C60 fullerene. The result of the Xe atom encapsulated inside C60 confirms the three main peaks observed in the recent measurement in the energy region of the Xe 4 d giant resonance and indicates the possibility that the Auger decay of the Xe+ has been greatly suppressed if the ion is encapsulated inside C60. It is suggested to use the current theoretical result around 22 eV to check this possibility.
Manipulation of transport hysteresis on graphene field effect transistors with Ga ion irradiation
Wang, Quan, E-mail: firstname.lastname@example.com [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Liu, Shuai; Ren, Naifei [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)
We have studied the effect of Ga ion irradiation on the controllable hysteretic behavior of graphene field effect transistors fabricated on Si/SO{sub 2} substrates. The various densities of defects in graphene were monitored by Raman spectrum. It was found that the Dirac point shifted to the positive gate voltage constantly, while the hysteretic behavior was enhanced first and then weakened, with the dose of ion irradiation increasing. By contrasting the trap charges density induced by dopant and the total density of effective trap charges, it demonstrated that adsorbate doping was not the decisive factor that induced the hysteretic behavior. The tunneling between the defect sites induced by ion irradiation was also an important cause for the hysteresis.
First tests of the ion irradiation and implantation beamline at the CMAM
NASA Astrophysics Data System (ADS)
Jiménez-Rey, D.; Benedicto, M.; Muñoz-Martín, A.; Bachiller-Perea, D.; Olivares, J.; Climent-Font, A.; Gómez-Ferrer, B.; Rodríguez, A.; Narros, J.; Maira, A.; Álvarez, J.; Nakbi, A.; Zucchiatti, A.; de Aragón, F.; García, J. M.; Vila, R.
The implantation and irradiation beamline of the Tandem ion accelerator of the Centro de Micro Análisis de Materiales (CMAM), in Madrid, has been recently completed with a beam sweep and monitoring system, and a cryostat/furnace. These new implementations convert the beamline into a versatile tool to implant ions, between H and Au2, in different materials with precise control of the sample temperature, which may be varied between -180 °C and 600 °C. The size of the swept area on target may be as large as 10 × 10 cm2. The implantation chamber also allows carrying out in situ or/and on line analyses during the irradiations by means of advanced optical measurements, as well as ion beam analyses (IBA). These advancements can be employed in novel applications such as the fabrication of optical waveguides and irradiation tests of structural and functional materials for future fusion reactors. The results of beam tests and first experiments are shown.
Automatic system for single ion/single cell irradiation based on Cracow microprobe
NASA Astrophysics Data System (ADS)
Veselov, O.; Polak, W.; Lekki, J.; Stachura, Z.; Lebed, K.; Stycze?, J.; Ugenskiene, R.
Recently, the Cracow ion microprobe has found its new application as a single ion hit facility (SIHF), allowing precise irradiations of living cells by a controlled number of ions. The instrument enables a broad field of research, such as survival studies, adaptive response investigations, bystander effect, inverse dose-rate effect, low-dose hypersensitivity, etc. This work presents principles of construction and operation of the SIHF based on the Cracow microprobe. We discuss some crucial features of optical, positioning, and blanking systems, including self-developed software responsible for semiautomatic cell recognition, for precise positioning of cells, and for controlling the irradiation process. We also show some tests carried out to determine the efficiency of the whole system and of its segments. In addition, we present results of the first irradiation measurements performed with living cells.
Biodamage via shock waves initiated by irradiation with ions
Surdutovich, Eugene; Yakubovich, Alexander V.; Solov'yov, Andrey V.
Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. PMID:23411473
Biodamage via shock waves initiated by irradiation with ions.
Surdutovich, Eugene; Yakubovich, Alexander V; Solov'yov, Andrey V
Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. PMID:23411473
Compositional analyses of ion-irradiation-induced phases in ?-Sc 4Zr 3O 12
K. E. Sickafus; M. Ishimaru; Y. Hirotsu; I. O. Usov; J. A. Valdez; P. Hosemann; A. L. Johnson; T. T. Thao
Compositional analyses were performed on a ?-Sc4Zr3O12 oxide sample following irradiation with 300keV Kr++ ions to a fluence of 3×1020Kr\\/m2 at cryogenic temperature (100K). Energy-dispersive X-ray spectroscopy (EDXS), Rutherford backscattering spectrometry (RBS) and depth profile X-ray photoelectron spectroscopy (XPS) analyses revealed that the cation sublattice in the near-surface region of the irradiated sample consists of at least 40% Zr. This
Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation
Zhang, Yanwen; Jiang, Weilin; Wang, Chong M.; Namavar, Fereydoon; Edmondson, Philip D.; Zhu, Zihua; Gao, Fei; Lian, Jie; Weber, William J.
Grain growth, oxygen stoichiometry and phase stability of nanostructurally-stabilized zirconia (NSZ) in pure cubic phase are investigated under 2 MeV Au ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with dose, and follows a power law (n=6) to a saturation value of ~30 nm that decreases with temperature. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that thermal grain growth is not activated and defect-stimulated grain growth is the dominating mechanism. While cubic phase is perfectly retained and no new phases are identified after the high-dose irradiations, reduction of oxygen in the irradiated NSZ films is detected. The ratio of O to Zr decreases from ~2.0 for the as-deposited films to ~1.65 after irradiation to ~35 dpa. Significant increase of oxygen vacancies in nanocrystalline zirconia suggests substantially enhanced oxygen diffusion under ion irradiation, a materials behavior far from equilibrium. The oxygen deficiency may be essential in stabilizing cubic phase to larger grain sizes.
Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots
Chowdhury, S. [Department of Physics, Gauhati University, Guwahati, Assam 781014 (India)], E-mail: email@example.com; Hussain, A.M.P. [Department of Physics, Gauhati University, Guwahati, Assam 781014 (India); Ahmed, G.A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784028 (India); Singh, F.; Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Choudhury, A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784028 (India)
The present study compares structural and optical modifications of bare and silica (SiO{sub 2}) coated ZnS quantum dots under swift heavy ion (SHI) irradiation. Bare and silica coated ZnS quantum dots were prepared following an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) study of the samples show the formation of almost spherical ZnS quantum dots. The UV-Vis absorption spectra reveal blue shift relative to bulk material in absorption energy while photoluminescence (PL) spectra suggests that surface state and near band edge emissions are dominating in case of bare and coated samples, respectively. Swift heavy ion irradiation of the samples was carried out with 160 MeV Ni{sup 12+} ion beam with fluences 10{sup 12} to 10{sup 13} ions/cm{sup 2}. Size enhancement of bare quantum dots after irradiation has been indicated in XRD and TEM analysis of the samples which has also been supported by optical absorption spectra. However similar investigations on irradiated coated quantum dots revealed little change in quantum dot size and emission. The present study thus shows that the coated ZnS quantum dots are stable upon SHI irradiation compared to the bare one.
Fabricating high-density magnetic storage elements by low-dose ion beam irradiation
Neb, R.; Sebastian, T.; Pirro, P.; Hillebrands, B. [Fachbereich Physik and Research Center Optimas, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 56, 67663 Kaiserslautern (Germany); Pofahl, S.; Schaefer, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Reuscher, B. [Institut fuer Oberflaechen-und Schichtanalytik, IFOS, Trippstadter Strasse 120, 67663 Kaiserslautern (Germany)
We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga{sup +}-ion beam to demonstrate the working principle for a storage array with a bit density of 7 Gbit/in.{sup 2}. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.
Interaction of deuterium with vacancies induced by ion irradiation in W
NASA Astrophysics Data System (ADS)
Xu, Q.; Sato, K.; Cao, X. Z.; Zhang, P.; Wang, B. Y.; Yoshiie, T.; Watanabe, H.; Yoshida, N.
The tritium inventory in plasma-facing materials (PFMs) is an important issue in fusion reactors. Tungsten (W), which is a candidate PFM, has a very low solubility for hydrogen isotopes, but intrinsic and radiation-induced defects can retain a significant amount of hydrogen. A positron annihilation technique was used to investigate the interactions between deuterium (D) and vacancies in W irradiated by Cu ions. The results indicated that vacancies were formed in W after Cu ion irradiation, and that D atoms were trapped by these vacancies.
Magnetic micropatterning of FeNi/FeMn exchange bias bilayers by ion irradiation
Mougin, A.; Poppe, S.; Fassbender, J.; Hillebrands, B.; Faini, G.; Ebels, U.; Jung, M.; Engel, D.; Ehresmann, A.; Schmoranzer, H.
Ion irradiation is an excellent tool to modify magnetic properties on the submicrometer scale, without modification of the sample topography. We utilize this effect to magnetically pattern exchange bias double layers using resist masks patterned by electron-beam lithography. Ion irradiation through the masks leads to a lateral modification of the magnetization reversal behavior and allows one to study the magnetization reversal as a function of the exchange bias field strength on a single sample. Results are presented on the macroscopic and microscopic magnetization reversal using the magneto-optic Kerr effect and magnetic force microscopy, respectively. {copyright} 2001 American Institute of Physics.
Enhancement of ferromagnetism in Pd nanoparticle by swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Kulriya, P. K.; Mehta, B. R.; Avasthi, D. K.; Agarwal, D. C.; Thakur, P.; Brookes, N. B.; Chawla, A. K.; Chandra, R.
In this study, the effect of swift heavy ion irradiation on the magnetic properties of the Pd nanoparticles has been investigated. Structural investigations along with superconducting quantum interface device measurements show that ferromagnetic properties of the Pd nanoparticles are due to the deviation of their electronic structure from that of bulk. The electronic structure is further modified due to the creation of defects on ion irradiation, which results in 20 times increase in the saturation magnetization. The present study establishes that the defect induced modification of Pd 4d electronic structure is responsible for the ferromagnetic properties of the Pd nanoparticles.
Combined High Pressure and Heavy-Ion Irradiation: a Novel Approach
Lang, M.; Zhang, F; Lian, J; Trautmann, C; Neumann, R; Ewing, R
Swift heavy-ion irradiations of a wide variety of materials have been used to modify and manipulate the properties of solids at the nanoscale. Recently, these high-energy irradiations have been successfully combined with high-pressure experiments. Based on results obtained for zircon (ZrSiO{sub 4}), this paper introduces this new experimental approach involving diamond anvil cells and large ion-accelerator facilities. This technique provides a wide spectrum of geoscience applications from nanoscale simulations of fission-track formation under crustal conditions to phase transitions of radiation-damaged minerals resulting from meteorite impact.
Impacts of Ion Irradiation on Hafnium oxide-based Resistive Random Access Memory Devices
NASA Astrophysics Data System (ADS)
He, Xiaoli
The impacts of ion irradiation on so-called vacancy-change mechanism (VCM) and electrochemical-metallization mechanism (ECM) ReRAM devices based on HfO2 are investigated using various ion sources: H + (1 MeV), He+ (1 MeV), N+ (1 MeV), Ne+ (1.6 MeV) and Ar+ (2.75 MeV) over a range of total doses (105 -- 1011 rad(Si)) and fluences (1012 -- 1015 cm-2). VCM-ReRAM devices show robust resistive switching function after all irradiation experiments. VCM resistive switching parameters including set voltage (V set), reset voltage (Vreset), on-state resistance (R on) and off-state resistance (Roff) exhibited, in most cases, modest changes after irradiation. Decreases in forming voltage (Vf) and initial resistance (Rfresh) of fresh devices were observed after all irradiation experiments on VCM-ReRAM devices with the exception of Ar+ irradiation at the highest fluence (10 15 cm-2). In that case Rfresh increased by an order of magnitude. For VCM-ReRAM devices it was also observed that irradiation beyond a dose threshold of approximately 5 Grad(Si) could induce off-to-on state transition events. This behavior could lead to errors in a VCM-ReRAM memory system. ECM-ReRAM devices (based on HfO2) were also subjected to ion irradiation. Under proton irradiation ECM-ReRAM devices remained functional, but with relatively large positive variations (20-40%) in Vset, Vreset and Ron and large negative variations (˜ -60%) in Roff. In contrast to VCM HfO2-ReRAMs, ECM-based devices exhibited increased V f after irradiation, and no off-to-on transitions were observed. Interestingly, for ECM-ReRAM devices, high-fluence Ar irradiation resulted in a transition of the electrical conduction mechanism associated with the conductive filament forming process from a Poole-Frenkel conduction mechanism (pre-irradiation) to ionic conduction (post-Ar irradiation). ECM-ReRAM devices irradiated with lighter ions did not exhibit this effect. The different ion irradiation responses of the two types of HfO2-ReRAMs studied originate from their distinct switching mechanisms -- vacancy filament switching for VCM-ReRAMs and metal filament switching for ECM-ReRAMs -- which respond differently to the irradiation-induced changes in the vacancy/defect densities and crystallite structures in HfO2. SRIM (Stopping and Range of Ions in Matter) modeling was used to roughly estimate the density of irradiation-induced vacancies. These model results correlated well with experimental observations in terms of vacancy defect density thresholds sufficient to impact ReRAM switching behavior. Physical characterization of pre- and post-irradiation ReRAM devices using techniques including XRD, AES, SEM, EDS, and SIMS were also employed to support the modeling and electrical measurements. This work suggests that HfO2-based ReRAM devices are a promising candidate for space and nuclear applications requiring a 'radiation-hard' memory technology.
Photoionization and predissociation of excited states of NeXe, ArXe, KrXe, and Xe2
NASA Astrophysics Data System (ADS)
Pratt, S. T.; Dehmer, P. M.; Dehmer, J. L.
The rare gas dimers nexe, ArXe, KrXe and Xe2 were studied using two-photon resonant, three photon (2+1) ionization in a time of flight mass spectrometer. New molecular band systems were identified in all four dimers. (AIP)
Defects in Cr-doped bismuth germanium oxide crystal irradiated by high energy 235U ions
NASA Astrophysics Data System (ADS)
Potera, P.; Piecuch, A.; Schwartz, K.
The present work is devoted to investigation of radiation defects in chromium doped Bi12GeO20 (BGO) single crystals absorbing in the spectral range 0.2...1.1 ?m induced under influence of the 235U ions irradiation with energy 9.35 MeV/u and a fluence 5×1011 cm-2. For comparison the changes of absorption spectra during irradiation by light from different sources due as radiation defects creation are studied. The effect of heating in air on the absorption spectrum of irradiated sample is also studied.
Study and optimization of ion-irradiated high Tc Josephson junctions by Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Sirena, M.; Bergeal, N.; Lesueur, J.; Faini, G.; Bernard, R.; Briatico, J.; Crete, D. G.; Contour, J. P.
High Tc Josephson junctions (HTc JJ) made by irradiation have remarkable properties for technological applications. However, the spread in their electrical characteristics increases with the ion dose. We present a simple model to explain the JJ inhomogeneities, which accounts quantitatively for experimental data. The spread in the slit's width of the irradiation mask is the limiting factor. Monte Carlo simulations have been performed using different irradiation conditions to study their influence on the spread of the JJ characteristics. A "universal" behavior has been evidenced, which allows us to propose new strategies to optimize JJ reproducibility.
Ion irradiation induced enhancement of out-of-plane magnetic anisotropy in ultrathin Co films
Mazalski, P.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Bialystok, Bialystok (Poland); Liedke, M. O.; Fassbender, J. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Baczewski, L. T.; Wawro, A. [Institute of Physics, Polish Academy of Science, Warszawa (Poland)
Ga{sup +} or He{sup +} irradiated MBE grown ultrathin films of sapphire/Pt/Co(d{sub Co})/Pt(d{sub Pt}) were studied using polar Kerr effect in wide ranges of both cobalt d{sub Co} and platinum d{sub Pt} thicknesses as well as ion fluences F. Two branches of increased magnetic anisotropy and enhanced Kerr rotation angle induced by Ga{sup +} or He{sup +} irradiation are clearly visible in two-dimensional (d{sub Co}, LogF) diagrams. Only Ga{sup +} irradiation induces two branches of out-of-plane magnetization state.
2 MeV ion irradiation effects on AlGaN/GaN HFET devices
NASA Astrophysics Data System (ADS)
Sonia, G.; Richter, E.; Brunner, F.; Denker, A.; Lossy, R.; Mai, M.; Lenk, F.; Bundesmann, J.; Pensl, G.; Schmidt, J.; Zeimer, U.; Wang, L.; Baskar, K.; Weyers, M.; Würfl, J.; Tränkle, G.
AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with 2 MeV protons, carbon, oxygen, iron and krypton ions with fluences ranging from 1 × 109 cm-2 to 1 × 1013 cm-2. DC, pulsed I-V characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured before and after irradiation. In parallel, a thick GaN reference layer was also irradiated with the same ions and was characterized by X-ray diffraction, photoluminescence, Hall measurements before and after irradiation. Small changes in the device performance were observed after irradiation with carbon and oxygen at a fluence of 5 × 1010 cm-2. Remarkable changes in device characteristics were seen at a fluence of 1 × 1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly, remarkable changes were also observed in the GaN layer for irradiations with fluence of 1 × 1012 cm-2. The results found on devices and on the GaN layer were compared and correlated.
Damage Profiles and Ion Distribution in Pt-irradiated SiC
Xue, Haizhou [University of Tennessee, Knoxville (UTK); Zhang, Yanwen [ORNL; Zhu, Zihua [Pacific Northwest National Laboratory (PNNL); Zhang, Weiming [Peking University; Bae, Dr. In-Tae [State University of New York, Binghamton; Weber, William J [ORNL
Single crystalline 6H-SiC samples were irradiated at 150 K using 2MeV Pt ions. Local volume swelling is determined by electron energy loss spectroscopy (EELS), a nearly sigmoidal dependence with irradiation dose is observed. The disorder profiles and ion distribution are determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy and secondary ion mass spectrum. Since the volume swelling reaches 12% over the damage region under high ion fluence, lattice expansion is considered and corrected during the data analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter). Comparing with the measured profiles, SRIM code significantly overestimates the electronic stopping power for the slow heavy Pt ions, and large derivations are observed in the predicted ion distribution and the damage profiles. Utilizing the reciprocity method that is based on the invariance of the inelastic excitation in ion atom collisions against interchange of projectile and target, much lower electronic stopping is deduced. A simple approach based on reducing the density of SiC target in SRIM simulation is proposed to compensate the overestimated SRIM electronic stopping power values. Better damage profile and ion range are predicted.
Damage Profiles and Ion Distribution in Pt-irradiated SiC
Xue, Haizhou; Zhang, Yanwen; Zhu, Zihua; Zhang, Weiming; Bae, In-Tae; Weber, William J.
Single crystalline 6H-SiC samples were irradiated at 150 K with 2 MeV Pt ions. The local volume swelling was determined by electron energy loss spectroscopy (EELS), and a nearly sigmoidal dependence on irradiation dose is observed. The disorder profiles and ion distribution were determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy, and secondary ion mass spectrometry. Since the volume swelling reaches 12% over the damage region at high ion fluence, the effect of lattice expansion is considered and corrected for in the analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter).When compared with the measured profiles, the SRIM code predictions of ion distribution and the damage profiles are underestimated due to significant overestimation of the electronic stopping power for the slow heavy Pt ions. By utilizing the reciprocity method, which is based on the invariance of the inelastic energy loss in ion-solid collisions against interchange of projectile and target atom, a much lower electronic stopping power is deduced. A simple approach, based on reducing the density of SiC target in SRIM simulation, is proposed to compensate the overestimated SRIM electronic stopping power values, which results in improved agreement between predicted and measured damage profiles and ion ranges.
Amorphization of nanocrystalline monoclinic ZrO2 by swift heavy ion irradiation.
Lu, Fengyuan; Wang, Jianwei; Lang, Maik; Toulemonde, Marcel; Namavar, Fereydoon; Trautmann, Christina; Zhang, Jiaming; Ewing, Rodney C; Lian, Jie
Bulk ZrO(2) polymorphs generally have an extremely high amorphization tolerance upon low energy ion and swift heavy ion irradiation in which ballistic interaction and ionization radiation dominate the ion-solid interaction, respectively. However, under very high-energy irradiation by 1.33 GeV U-238, nanocrystalline (40-50 nm) monoclinic ZrO(2) can be amorphized. A computational simulation based on a thermal spike model reveals that the strong ionizing radiation from swift heavy ions with a very high electronic energy loss of 52.2 keV nm(-1) can induce transient zones with temperatures well above the ZrO(2) melting point. The extreme electronic energy loss, coupled with the high energy state of the nanostructured materials and a high thermal confinement due to the less effective heat transport within the transient hot zone, may eventually be responsible for the ionizing radiation-induced amorphization without transforming to the tetragonal polymorph. The amorphization of nanocrystalline zirconia was also confirmed by 1.69 GeV Au ion irradiation with the electronic energy loss of 40 keV nm(-1). These results suggest that highly radiation tolerant materials in bulk forms, such as ZrO(2), may be radiation sensitive with the reduced length scale down to the nano-metered regime upon irradiation above a threshold value of electronic energy loss. PMID:22858872
AC-transport measurements of ion beam irradiated GaMnAs semiconductors
NASA Astrophysics Data System (ADS)
Sinnecker, Elis; Santánna, Marcelo; Rappoport, Tatiana; Mendes, Joaquim; Pires, Mauricio; Penello, Germano; Souza, Deivid; Mello, Sergio; Furdyna, Jacek; Liu, Xinyu
GaMnAs is a diluted magnetic semiconductors in which lattice atoms have been partially substituted by magnetic atoms, thus inserting a local magnetic moment into the lattice. Recently it was shown that ion beam irradiation can be an effective tool to modify the magnetic and electronic properties of Ga1-xMnxAs thin films. We observed that an increase of the structural disorder by irradiation leads to a systematic decrease on the saturation magnetization. Here, we provide further information on the electronic properties of irradiated samples. Measurements of ac-resistivity, magnetoresistance and Hall resistance were performed from 5K to 300K applying a DC magnetic field up to 7T. The results show an interesting frequency dependence of the ac-transport of measured irradiated samples. For the sake of comparison, data on irradiated non-magnetic semiconductor, grown on the same conditions as Ga1-xMnxAs thin films, are provided. GaMnAs is a diluted magnetic semiconductors in which lattice atoms have been partially substituted by magnetic atoms, thus inserting a local magnetic moment into the lattice. Recently it was shown that ion beam irradiation can be an effective tool to modify the magnetic and electronic properties of Ga1-xMnxAs thin films. We observed that an increase of the structural disorder by irradiation leads to a systematic decrease on the saturation magnetization. Here, we provide further information on the electronic properties of irradiated samples. Measurements of ac-resistivity, magnetoresistance and Hall resistance were performed from 5K to 300K applying a DC magnetic field up to 7T. The results show an interesting frequency dependence of the ac-transport of measured irradiated samples. For the sake of comparison, data on irradiated non-magnetic semiconductor, grown on the same conditions as Ga1-xMnxAs thin films, are provided. 00879
Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Ochedowski, Oliver; Osmani, Orkhan; Schade, Martin; Bussmann, Benedict Kleine; Ban-D'Etat, Brigitte; Lebius, Henning; Schleberger, Marika
The controlled creation of defects in silicon carbide represents a major challenge. A well-known and efficient tool for defect creation in dielectric materials is the irradiation with swift (Ekin?500?keV/amu) heavy ions, which deposit a significant amount of their kinetic energy into the electronic system. However, in the case of silicon carbide, a significant defect creation by individual ions could hitherto not be achieved. Here we present experimental evidence that silicon carbide surfaces can be modified by individual swift heavy ions with an energy well below the proposed threshold if the irradiation takes place under oblique angles. Depending on the angle of incidence, these grooves can span several hundreds of nanometres. We show that our experimental data are fully compatible with the assumption that each ion induces the sublimation of silicon atoms along its trajectory, resulting in narrow graphitic grooves in the silicon carbide matrix.
Effect of ?-irradiation of ion imprinted polymer (IIP) particles for the preconcentrative separation of dysprosium from other selected lanthanides
V. M Biju; J. Mary Gladis; T. Prasada Rao
The selectivity of zinc with respect to copper ions was improved by ?-irradiation of surface imprinted polymer particles. We have reported the preparation of dysprosium ion imprinted polymer (IIP) particles by covalent approach during molecular imprinting. This paper reports the results obtained after ?-irradiation of dysprosium IIP particles and their use in the preconcentration\\/separation of dysprosium from dilute aqueous solutions
Colloidal assemblies modied by ion irradiation E. Snoeks a
Polman, Albert
possible, as we will show. 2. Experimental Two dispersions of colloidal silica (SiO2) spheres in ethanol for free-stand- ing thin ®lms composed of a metallic glass irradi- ated at energies of several 100 MeV [2
CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Surface Disorder of GaN Irradiated by Highly Charged Ar2+Ions
Li-Qing Zhang; Chong-Hong Zhang; Yi-Tao Yang; Cun-Feng Yao; Bing-Sheng Li; You-Mei Sun; Shu-Jian Song
The surface damage to gallium nitride films irradiated by Arq+ (6 <= q <= 16) ions at room temperature is studied by the atomic force microscopy. It is found that when charge state exceeds a threshold value, significant swelling was turned into obvious erosion in the irradiated region. The surface change of the irradiated region strongly depends on the charge
Volatile evolution induced by energetic He ++ ions in a polyurethane and the effects of previous gamma irradiation
J. J. Murphy; C. J. Wetteland
Irradiation of polymer samples using an accelerated beam of He++ ions passed through a 10?m thick window of havar foil, has been performed. Such an irradiation simulates the effects of large ? radiation doses, on a vastly reduced time-scale. The experimental set up was designed to allow analysis of volatiles evolved from the irradiated samples by means of a residual
Evolution of Crystallinity and Texturing on 120 MeV Au Ion Irradiation on NiO Thin Films
NASA Astrophysics Data System (ADS)
Mallick, P.; Rath, Chandana; Agarwal, D. C.; Biswal, R.; Behera, D.; Avasthi, D. K.; Kanjilal, D.; Satyam, P. V.; Mishra, N. C.
NiO thin films grown on Si(100) substrate by electron beam evaporation and sintered at 500 °C and 700 °C were irradiated with 120 MeV 197Au9+ ions. The FCC structure of the sintered films was retained up to the highest fluence (3 × l013 ions.cm-2) of irradiation. As against the expected amorphization due to ion irradiation when electronic energy loss exceeds certain threshold value, we observe an improvement of crystallinity and grain orientation at certain fluences of irradiation.
Gas separation in nanoporous membranes formed by etching ion irradiated polymer foils
W. Ensinger; R. Sudowe; R. Brandt; R. Neumann
Polymer membranes with pores with radii in the range of several 10–100nm were formed by irradiating polyimide foil with highly energetic heavy ions and etching the latent ion tracks with hypochlorite. The aerial density of the pores could be chosen up to an upper limit of 108porescm?2, at which too many pores start to overlap. The straight cylindrical pores were
Static elasticity of cordierite I: Effect of heavy ion irradiation on the compressibility of hydrous cordierite
NASA Astrophysics Data System (ADS)
Miletich, R.; Scheidl, K. S.; Schmitt, M.; Moissl, A. P.; Pippinger, T.; Gatta, G. D.; Schuster, B.; Trautmann, C.
The effect of ion beam irradiations on the elastic properties of hydrous cordierite was investigated by means of Raman and X-ray diffraction experiments. Oriented single crystals were exposed to swift heavy ions (Au, Bi) of various specific energies (10.0-11.1 MeV/u and 80 MeV/u), applying fluences up to 5 × 1013 ions/cm2. The determination of unit-cell constants yields a volume strain of 3.4 × 10-3 up to the maximum fluence, which corresponds to a compression of non-irradiated cordierite at ~480 ± 10 MPa. The unit-cell contraction is anisotropic ( e 1 = 1.4 ± 0.1 × 10-3, e 2 = 1.5 ± 0.1 × 10-3, and e 3 = 7 ± 1 × 10-4) with the c-axis to shrink only half as much as the axes within the ab-plane. The lattice elasticity for irradiated cordierite ( ? = 1 × 1012 ions/cm2) was determined from single-crystal XRD measurements in the diamond anvil cell. The fitted third-order Birch-Murnaghan equation-of-state parameters of irradiated cordierite ( V 0 = 1548.41 ± 0.16 Å3, K 0 = 117.1 ± 1.1 GPa, ? K/? P = -0.6 ± 0.3) reveal a 10-11 % higher compressibility compared to non-irradiated cordierite. While the higher compressibility is attributed to the previously reported irradiation-induced loss of extra-framework H2O, the anomalous elasticity as expressed by elastic softening ( ? {a/-1}, ? {b/-1}, ? {c/-1} = 397 ± 9, 395 ± 28, 308 ± 11 GPa, ?( ? -1)/? P = -4.5 ± 2.7, -6.6 ± 8.4, -5.4 ± 3.0) appears to be related to the framework stability and to be independent of the water content in the channels and thus of the ion beam exposure.
Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation
NASA Astrophysics Data System (ADS)
Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm
Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, ??, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.
Purification/annealing of graphene with 100-MeV Ag ion irradiation
NASA Astrophysics Data System (ADS)
Kumar, Sunil; Tripathi, Ambuj; Singh, Fouran; Khan, Saif Ahmad; Baranwal, Vikas; Avasthi, Devesh Kumar
Studies on interaction of graphene with radiation are important because of nanolithographic processes in graphene-based electronic devices and for space applications. Since the electronic properties of graphene are highly sensitive to the defects and number of layers in graphene sample, it is desirable to develop tools to engineer these two parameters. We report swift heavy ion (SHI) irradiation-induced annealing and purification effects in graphene films, similar to that observed in our studies on fullerenes and carbon nanotubes (CNTs). Raman studies after irradiation with 100-MeV Ag ions (fluences from 3 × 1010 to 1 × 1014 ions/cm2) show that the disorder parameter ?, defined by I D/ I G ratio, decreases at lower fluences but increases at higher fluences beyond 1 × 1012 ions/cm2. This indicates that SHI induces annealing effects at lower fluences. We also observe that the number of graphene layers is reduced at fluences higher than 1 × 1013 ions/cm2. Using inelastic thermal spike model calculations, we estimate a radius of 2.6 nm for ion track core surrounded by a halo extending up to 11.6 nm. The transient temperature above the melting point in the track core results in damage, whereas lower temperature in the track halo is responsible for annealing. The results suggest that SHI irradiation fluence may be used as one of the tools for defect annealing and manipulation of the number of graphene layers.
Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties
McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward; Liu, Kai
A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the nanocluster films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.
Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties
NASA Astrophysics Data System (ADS)
McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward C.; Liu, Kai
A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NCs) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the NC films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.
Carbon (70 MeV) and copper (120 MeV) ions irradiation effects in Makrofol-N
NASA Astrophysics Data System (ADS)
Singh, Lakhwant; Samra, Kawaljeet Singh; Singh, Ravinder; Kumar, Ramneek
Makrofol-N polycarbonate was irradiated with carbon (70 MeV) and copper (120 MeV) ions to analyze the induced effects with respect to optical and structural properties. In the present investigation, the fluence for carbon and copper beams was kept in the range of 1×1011- 1×1013 ions/cm2 to study the swift heavy ion induced modifications. UV-VIS, FTIR and XRD techniques were utilized to study the induced changes. The analysis of UV-VIS absorption studies revealed that the optical energy gap was reduced by 17% on carbon irradiation, whereas the copper beam leads to a decrease of 52% at the highest fluence of 1×1013 ions/cm2. The band gap can be correlated to the number of carbon atoms, N, in a cluster with a modified Robertson's equation. In copper (120 MeV) ions irradiated polycarbonate, the number of carbon atoms in a cluster was increased from 63 to 269 with the increase of ion fluence from 0 to 1×1013 ions/cm2, whereas N is raised only up to 91 when the same polymer films were irradiated with carbon (70 MeV) ions under similar conditions. FTIR analysis showed a decrease in almost all characteristic absorption bands under irradiation. The formation of hydroxyl (- OH) and alkene (CDC) groups were observed in Makrofol-N at higher fluence on irradiation with both types of ions, while the formation alkyne end (R- C? CH) group was observed only after copper ions irradiation. The radii of the alkyne production of about 3.3 nm were deduced for copper (120 MeV) ions. XRD measurements show a decrease in intensity of the main peak and an increase of the average intermolecular spacing with the increase of ion fluence, which may be attributed to the structural degradation of Makrofol-N on swift ion irradiation.
Atomistic modeling of nanoscale patterning of L1{sub 2} order induced by ion irradiation
Ye Jia [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lawrence Berkeley Laboratory, Berkeley, California 94720-8250 (United States); Li Youhong [Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Engineered Material Arresting Systems, Zodiac Aerospace, Logan Township, New Jersey 08085 (United States); Averback, Robert; Zuo Jianmin [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Bellon, Pascal [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
Theoretical predictions indicate that ordered alloys can spontaneously develop a steady-state nanoscale microstructure when irradiated with energetic particles. This behavior derives from a dynamical competition between disordering in cascades and thermally activated reordering, which leads to self-organization of the chemical order parameter. We test this possibility by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. We first generate realistic distributions of disordered zones for Ni{sub 3}Al irradiated with 70 keV He and 1 MeV Kr ions using MD and then input this data into KMC to obtain predictions of steady state microstructures as a function of the irradiation flux. Nanoscale patterning is observed for Kr ion irradiations but not for He ion irradiations. We illustrate, moreover, using image simulations of these KMC microstructures, that high-resolution transmission electron microscopy can be employed to identify nanoscale patterning. Finally, we indicate how this method could be used to synthesize functional thin films, with potential for magnetic applications.
Effects of ion irradiation on the mechanical properties of several polymers
NASA Astrophysics Data System (ADS)
Sasuga, Tsuneo; Kawanishi, Shunichi; Nishii, Masanobu; Seguchi, Tadao; Kohno, Isao
The effects of high-energy ion irradiation (8 MeV protons, 30 MeV He 2+, 80 MeV C 4+, and N 4+) on the tensile properties of polymers were studied under conditions in which ions should pass completely through the specimen and the results were compared with 2 MeV electron irradiation effects. Experiments were carried out on polymers having various constituents and molecular structures, i.e. eight aliphatic polymers and four aromatic polymers. In the aliphatic polymers studied (PE, PP, PVdF, ETFE, EVA, nylon-6, EPDM, and PE-TPE), there was scarcely any difference in the dose dependence of the tensile strength and ultimate elongation between proton and electron irradiation. In aromatic polymers (PET, PES, U-PS, and U-polymer), however, the decrements in the tensile strength and ultimate elongation vs proton dose were less than those for electron irradiation. In heavy-ion irradiation, the radiation damage of PE (an aliphatic polymer) decreased with increase of LET, but no obvious LET effects were observed in PES (an aromatic polymer).
Swift heavy-ion irradiation-induced shape and structural transformation in cobalt nanoparticles
Sprouster, D.J.; Giulian, R.; Araujo, L.L.; Kluth, P.; Johannessen, B.; Cookson, D.J.; Ridgway, M.C. (Aust. Synch.); (ANU)
The shape and structural evolution of Co nanoparticles embedded in SiO{sub 2} and subjected to swift heavy-ion irradiation have been investigated over a wide energy and fluence range. Modifications of the nanoparticle size and shape were characterized with transmission electron microscopy and small-angle x-ray scattering. Nanoparticles below a threshold diameter remained spherical in shape and progressively decreased in size under irradiation due to dissolution. Nanoparticles above the threshold diameter transformed into nanorods with their major dimension parallel to the incident ion direction. Modifications of the atomic-scale structure of the Co nanoparticles were identified with x-ray absorption spectroscopy. Analysis of the x-ray absorption near-edge spectra showed that prior to irradiation all Co atoms were in a metallic state, while after irradiation Co atoms were in both oxidized and metallic environments, the former consistent with dissolution. The evolution of the nanoparticle short-range order was determined from extended x-ray absorption fine structure spectroscopy. Structural changes in the Co nanoparticles as a function of ion fluence included an increase in disorder and asymmetric deviation from a Gaussian interatomic distance distribution coupled with a decrease in bondlength. Such changes resulted from the irradiation-induced decrease in nanoparticle size and subsequent dissolution.
Lifetime and transition probability determination in Xe IX
H.-P. Garnir; S. Enzonga Yoca; P. Quinet; É. Biémont
A new set of transition probabilities is proposed for Xe IX. They have been calculated by two different theoretical approaches i.e. a fully relativistic multiconfiguration Dirac–Fock (MCDF) method and a partly relativistic Hartree–Fock (HFR) approach taking core-polarization effects into account. Their accuracy has been evaluated through comparisons with lifetime measurements for 11 levels performed using beams of Xe+ ions produced
n-Selective Single Capture Following Xe{sup 18+} And Xe{sup 54+} Impact On Na(3s) And Na*(3p)
Otranto, S. [CONICET and Dto. de Fisica, Universidad Nacional del Sur, 8000 Bahia Blanca (Argentina); Olson, R. E. [Physics Department, Missouri University of Science and Technology, Rolla, MO 65401 (United States); Hasan, V. G.; Hoekstra, R. [KVI-Atomic and Molecular Physics, University of Groeningen (Netherlands)
State selective single charge exchange n-level cross sections are calculated for collisions of Xe18+ and Xe54+ ions with Na(3s) and Na*(3p) over the energy range of 0.1 to 10.0 keV/amu. The CTMC method is used which includes all two-body interactions. Experimental state-selective cross sections and their corresponding transverse momentum spectra for Xe18+ are found to be in reasonable accord with the calculations.
Damage induced by electronic excitation in ion-irradiated yttria-stabilized zirconia
S. Moll; L. Thomé; L. Vincent; F. Garrido; G. Sattonnay; T. Thomé; J. Jagielski; J. M. Costantini
This article presents a study of the damage production in yttria-stabilized cubic zirconia single crystals irradiated with swift heavy ions. The combination of techniques which probe the material at different spatial scales (Rutherford backscattering spectrometry in channeling geometry, x-ray diffraction, transmission electron microscopy, and atomic force microscopy) was used in order to gain information about the damage depth distribution, the
In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams
Jiang, Weilin; Sundararajan, Jennifer A.; Varga, Tamas; Bowden, Mark E.; Qiang, You; McCloy, John S.; Henager, Charles H.; Montgomery, Robert O.
An in-situ study is reported on the structural evolution in nanocluster films under He+ ion irradiation using an advanced helium ion microscope. The films consist of loosely interconnected nanoclusters of magnetite or iron-magnetite (Fe-Fe3O4) core-shells. The nanostructure is observed to undergo dramatic changes under ion-beam irradiation, featuring grain growth, phase transition, particle aggregation, and formation of nanowire-like network and nano-pores. Studies based on ion irradiation, thermal annealing and election irradiation have indicated that the major structural evolution is activated by elastic nuclear collisions, while both electronic and thermal processes can play a significant role once the evolution starts. The electrical resistance of the Fe-Fe3O4 films measured in situ exhibits a super-exponential decay with dose. The behavior suggests that the nanocluster films possess an intrinsic merit for development of an advanced online monitor for neutron radiation with both high detection sensitivity and long-term applicability, which can enhance safety measures in many nuclear operations.
Transient heating and melting transformations in argon-ion laser irradiation of polysilicon films
Xu, Xianfan
Transient heating and melting transformations in argon-ion laser irradiation of polysilicon films recrystallize thin semi- conductor layers on insulators, such as oxidized wafers and bulk amorphous substrates in an inert gas environment at elevated temper- atures, up to 1400 K. High-speed photographic observa- tions
Nanoscale manipulation of Ge nanowires by ion irradiation Lucia Romano,1,a
Florida, University of
Nanoscale manipulation of Ge nanowires by ion irradiation Lucia Romano,1,a Nicholas G. Rudawski,2,b and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to fully direction. This effect demonstrates the detailed manipulation of nanoscale structures is possible through
Switching of the natural nanostructure in Bi2Te3 materials by ion irradiation.
Aabdin, Zainul; Peranio, Nicola; Eibl, Oliver
In Bi(2)Te(3) materials the natural nanostructure (nns) with a wavelength of 10 nm can be reproducibly switched ON and OFF by Ar(+) ion irradiation at 1.5 and 1 keV. Controlled formation of the nns in Bi(2)Te(3) materials has potential for reducing its thermal conductivity and could increase the thermoelectric figure of merit. PMID:22718358
Carbon Ion Irradiation Inhibits Glioma Cell Migration Through Downregulation of Integrin Expression
Rieken, Stefan, E-mail: email@example.com [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Habermehl, Daniel; Wuerth, Lena [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Brons, Stephan [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Mohr, Angela; Lindel, Katja; Weber, Klaus [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Haberer, Thomas [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Debus, Juergen; Combs, Stephanie E. [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany)
Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration. Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. Results: Single photon doses of 2 Gy and 10 Gy enhanced {alpha}{sub {nu}}{beta}{sub 3} and {alpha}{sub {nu}}{beta}{sub 5} integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn. Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.
Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions
NASA Astrophysics Data System (ADS)
Newby, Pascal J.; Canut, Bruno; Bluet, Jean-Marie; Gomès, Séverine; Isaiev, Mykola; Burbelo, Roman; Termentzidis, Konstantinos; Chantrenne, Patrice; Fréchette, Luc G.; Lysenko, Vladimir
In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 °C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.
TEM investigation on the microstructural evolution of Hastelloy N induced by Ar? ion irradiation.
Liu, Min; Lu, Yanling; Liu, Renduo; Zhou, Xingtai
Hastelloy N alloy has been selected as the primary structure material for molten salt reactor. In this article, Hastelloy N alloy samples were irradiated to different doses at room temperature using 300 keV Ar(+) ions. The microstructural evolution was investigated by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). Black dot defects emerged in sample irradiated at low dose (0.4 displacement per atom (dpa)), and they grew up with irradiation doses (0.4-2 dpa). A high density of small dislocation loops (nano meters in size) were observed in the sample irradiated to 4 dpa. When the ion dose increased to 12 dpa, complicated structures with defects (including dislocation lines, larger loops and smaller black dots) were observed. Dislocation networks were detected from high-angle annular dark field (HAADF) images. Larger dislocation loops (size: 30-80 nm) were visible in the sample irradiated to 40 dpa. Irradiation with dose of 120 dpa led to the formation of face-centered cubic nanocrystallites with preferred orientations. PMID:24285574
Polymer surfaces graphitization by low-energy He+ ions irradiation
NASA Astrophysics Data System (ADS)
Geworski, A.; Lazareva, I.; Gieb, K.; Koval, Y.; Müller, P.
The electrical and optical properties of surfaces of polyimide and AZ5214e graphitized by low-energy (1 keV) He+ irradiation at different polymer temperatures were investigated. The conductivity of the graphitized layers can be controlled with the irradiation temperature within a broad range and can reach values up to ˜1000 S/cm. We show that the electrical transport in low-conducting samples is governed by thermally activated hopping, while the samples with a high conductivity show a typical semimetallic behavior. The transition from thermally activated to semimetallic conductance governed by the irradiation temperature could also be observed in optical measurements. The semimetallic samples show an unusually high for graphitic materials carrier concentration, which results in a high extinction coefficient in the visible light range. By analyzing the temperature dependence of the conductance of the semimetallic samples, we conclude that the scattering of charge carriers is dominated by Coulomb interactions and can be described by a weak localization model. The transition from a three to two dimensional transport mechanism at low temperatures consistently explains the change in the temperature dependence of the conductance by cooling, observed in experiments.
MeV H+ ion irradiation effect on the stoichiometry of polyethylene terephthalate films
NASA Astrophysics Data System (ADS)
Abdesselam, M.; Muller, D.; Djebara, M.; Ouichaoui, S.; Chami, A. C.
Appropriate experimental conditions have been chosen to investigate the influence of main H+ ion irradiation parameters on stoichiometry changes induced in polyethylene terephthalate (PET) thin films. Stacks of six self-supporting identical films were irradiated perpendicularly to the target surface. Thus, the irradiations were realized simultaneously at different values of the target electronic stopping power, ?+. Indeed, the initial H+ ion energy of 1.1 MeV incident on the front polymer film was degraded down to 0.48 MeV at the entrance of the rear stacked film, which corresponds to an increase of ?+ from ˜0.22 up to ˜0.41 MeV cm2 mg-1. Ion fluences in the range (0.05-4) × 1015 cm-2 corresponding to an ion dose interval 1.80-263 MGy were used. The (H, O, C) atomic surface densities of the PET polymeric films were quantitatively determined by IBA techniques using a 1.62 MeV deuteron beam leading to the following main results: for each target film stacked at a given position thus fixed ?+, the oxygen atomic density decreases linearly versus ion fluence, ?; for the different ?+, the hydrogen impoverishment of the PET target is insignificant below critical fluence ?c ˜ 1.5 × 1015 cm-2 and becomes substantial above ?c; for fixed ?, the hydrogen and oxygen atomic densities exhibit linear decreases versus ?+; all measured such data versus ? and ?+ merge together into a unique decreasing curve for each (H, O, C) polymer content element when represented in function of the H+ ion dose, D, tightly correlating the latter two parameters; the O content element release from the PET target appears to be the most important, followed by the H content depletion, while the target C content is least affected under H+ ion irradiation.
Effects of heavy ion irradiation on amorphous hydrogenated (diamondlike) carbon films
Prawer, S.; Kalish, R.; Adel, M.; Richter, V.
Energetic ion-beam irradiation of diamondlike carbon thin films induces a decrease of 5--6 orders of magnitude in the resistivity of the films from their as-grown value of 10/sup 7/ ..cap omega.. cm. Diagnostics used to characterize the nature of the transformation included optical absorption measurements (band gap), Raman spectroscopy (microcrystalline structure), Rutherford backscattering spectroscopy (hydrogen content of the films), and measurements of the temperature dependence of the conductivity (electronic structure). It was found that the initial decrease in resistivity with an increasing ion dose is due to the loss of hydrogen from the films, with a concomitant decrease in the optical band gap. Heating the films during the irradiation greatly accelerates the rate of hydrogen loss as a function of dose. Once the hydrogen removal is complete, further irradiation increases the film conductivity by inducing the growth of microcrystallites of graphite.
Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine
Rodriguez-Fernandez, Luis [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico D.F., 01000 (Mexico)
Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.
Effect of pulsed ion irradiation on the electronic structure of multi-walled carbon nanotubes
NASA Astrophysics Data System (ADS)
Bolotov, V. V.; Korusenko, P. M.; Nesov, S. N.; Povoroznyuk, S. N.
The effect of pulsed ion irradiation and vacuum annealing on the ratio of sp 2- and sp 3-hybridized orbitals of carbon atoms in the layers of oriented multi-walled carbon nanotubes has been studied by analyzing the photoemission spectra of the C1 s core level and the valence band of carbon, which were obtained using the equipment of the BESSY II Russian-German beamline of synchrotron radiation and a Riber analytical system. It has been shown that the ion irradiation leads to a significant decrease in the fraction of atoms with the sp 3 hybridization of electrons. On the contrary, the annealing reduces the fraction of the sp 3-component in the spectra of carbon. Typical features of the valence band of multi-walled carbon nanotubes in the annealed and irradiated states have been established.
He+–ion irradiation effect on intersubband transitions in GaAs\\/AlGaAs multiple quantum wells
Y. Berhane; M. O. Manasreh; B. D. Weaver
Intersubband transitions in 3 MeV He+–ion irradiated GaAs–AlGaAs multiple quantum wells were studied using an optical absorption technique. The intersubband transitions were completely depleted in samples irradiated with doses as low as 1×1014 cm?2. Thermal annealing recovery of intersubband transitions was observed in samples irradiated with lower doses. On the other hand, intersubband transitions in heavily irradiated (doses>3×1014 cm?2) samples
He+-ion irradiation effect on intersubband transitions in GaAs\\/AlGaAs multiple quantum wells
Y. Berhane; M. O. Manasreh; B. D. Weaver
Intersubband transitions in 3 MeV He+-ion irradiated GaAs-AlGaAs multiple quantum wells were studied using an optical absorption technique. The intersubband transitions were completely depleted in samples irradiated with doses as low as 1×1014 cm-2. Thermal annealing recovery of intersubband transitions was observed in samples irradiated with lower doses. On the other hand, intersubband transitions in heavily irradiated (doses>3×1014 cm-2) samples
1\\/ f noise studies of swift heavy ion irradiated magnetite thin films
M. Wasi Khan; Ravi Kumar; J. P. Srivastava; S. K. Arora; R. J. Choudhary; I. V. Shvets
The effect of 190MeV 107Ag ion irradiation on antiphase boundaries (APBs) of epitaxial Fe3O4 thin films (thickness ?70nm) grown on MgO (100) oriented substrate has been investigated. The X-ray diffraction shows that at low fluence values upto 5×1011ions\\/cm2, the strain in the films is relaxed whereas at high fluence 1×1012ions\\/cm2, the epitaxial relationship with the substrate is decreasing. The low
Thickness dependent effect of swift heavy ion irradiation in W/Ni superlattice multilayers
NASA Astrophysics Data System (ADS)
Bagchi, Sharmistha; Singh, F.; Avasthi, D. K.; Lalla, N. P.
This study reports on the layer thickness dependent effect of swift heavy ion irradiation (SHI) in W/Ni multilayer structures (MLS) having bilayer compositions of [W(25 Å)/Ni(25 Å)], [W(40 Å)/Ni(40 Å)] and [W(34 Å)/Ni(57 Å)] of 10-bilayers. These were grown on [1 0 0]-silicon using ion-beam sputtering. The pristine MLS were subjected to 120 MeV Au9+ ion irradiation up to a fluence of 1 × 1014 ions cm-2. Structural characterization of pristine and irradiated MLS was carried out employing wide-angle x-ray diffraction (WAXD), x-ray reflectivity (XRR) and cross-sectional transmission electron microscopy (X-TEM). The XRR studies reveal a decreasing trend in the SHI-induced interface roughness of MLS with thicker Ni layers. This effect is vividly clear in the WAXD and X-TEM studies. The X-TEM studies reveal thickness dependent microstructural changes in the MLS. The MLS with thinner bilayers undergo intra-layer microstructure changes from textured to nano-crystalline on irradiation whereas the MLS with thicker bilayers remain intact although the irradiation fluence is the same. This effect has been cross-verified, beyond all doubts, by studying the SHI irradiation effect on a MLS having a composite bilayer structure of [W(50 Å)/Ni(50 Å)]5BL/W(25 Å)/Ni(25 Å)]5BL]/Si grown over each other. The observed nano-crystallization has been attributed to thermal spike caused by large electronic energy deposition. Our analysis clearly reveals that the effect of SHI strongly depends on the layer thickness of the multilayers.
Characterization of ion-irradiated poly-L-lactic acid using nano-cutting.
Saito, F; Yotoriyama, T; Nishiyama, I; Suzuki, Y; Goto, A; Nagashima, Y; Hyodo, T
Effects on the mechanical strength of poly-L-lactic acid (PLLA) upon irradiation with 150 keV He(+) ion were studied. Changes in the irradiated surface were investigated using a surface texture and contour measuring instrument and an atomic force microscope. Observations made with the atomic force microscope revealed that the irradiated surface subsided significantly as the fluence increased. In order to investigate the dependence on fluence of the depth of the Bragg peak for the ion implantation, the cutting strength, ?, was analysed [F. Saito, I. Nishiyama and T. Hyodo, Mater. Lett., 2012, 66, 144-146]; this value is an indicator of the strength of a material against cutting, and is obtained from the cutting resistance. The averaged ion projected range increased from about 1.1 ?m for a fluence of 1 × 10(15) He(+)/cm(2) to about 4 ?m for a fluence of 1 × 10(16) He(+)/cm(2). The density of the region following irradiation was estimated using a combination of cutting resistance measurements and positron annihilation ? ray Doppler broadening measurements made with an energy-variable positron beam. The density decreased from the value of 1.27 g cm(-3) to about 0.6 g cm(-3) after irradiation with a fluence of 3 × 10(15) He(+)/cm(2). By considering the decrease in the density and the subsidence of the surface, it is concluded that only 30% of the original weight remained in the irradiated region after exposure to the He(+) ions. Anisotropic change in the cutting resistance suggests that mechanical strength in the direction normal to the surface increased while that in the lateral direction decreased. PMID:25380102
Iron ion irradiation increases promotes adhesion of monocytic cells to arterial vascular endothelium
NASA Astrophysics Data System (ADS)
Kucik, Dennis; Khaled, Saman; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz
Radiation causes inflammation, and chronic, low-level vascular inflammation is a risk factor for atherosclerosis. Consistent with this, exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Part of the inflammatory response to radiation is a change in the adhesiveness of the endothelial cells that line the blood vessels, triggering inappropriate accumulation of leukocytes, leading to later, damaging effects of inflammation. Although some studies have been done on the effects of gamma irradiation on vascular endothelium, the response of endothelium to heavy ion radiation likely to be encountered in prolonged space flight has not been determined. We investigated how irradiation of aortic endothelial cells with iron ions affects adhesiveness of cultured aortic endothelial cells for monocytic cells and the consequences of this for development of atherosclerosis. Aortic endothelial cells were irradiated with 600 MeV iron ions at Brookhaven National Laboratory and adhesion-related changes were measured. Cells remained viable for at least 72 hours, and were even able to repair acute damage to cell junctions. We found that iron ion irradiation altered expression levels of specific endothelial cell adhesion molecules. Further, these changes had functional consequences. Using a flow chamber adhesion assay to measure adhesion of monocytic cells to endothelial cells under physiological shear stress, we found that adhesivity of vascular endothelium was enhanced in as little as 24 hours after irradiation. Further, the radiation dose dependence was not monotonic, suggesting that it was not simply the result of endothelial cell damage. We also irradiated aortic arches and carotid arteries of Apolipoprotein-E-deficient mice. Histologic analysis of these mice will be conducted to determine whether effects of radiation on endothelial adhesiveness result in consequences for development of atherosclerosis. (Supported by NSBRI: NCC-9-58-162)
Ion dose dependence of the sputtering yield: Ar{sup +}, Ne{sup +}, and Xe{sup +} bombardment of Ru(0001) and Al(111)
Burnett, J.W.; Pellin, M.J.; Whitten, J.E.; Gruen, D.M. [Argonne National Lab., IL (United States); Yates, J.T. Jr. [Univ. of Pittsburgh, PA (United States)
The sputtering yield from clean metal surfaces has long been considered to be insensitive to primary ion dose at moderate ion fluences (< 10{sup 18} ions/cm{sup 2}). Using carefully cleaned and well-characterized targets, the ion dose dependence of the sputtering yield of Ru(0001) and Al(111) has been investigated. The sputtering yield of Ru(0001) is found to decrease substantially following primary ion bombardment at low fluences, while the sputtering yield of Al(111) exhibits no fluence dependence at low primary ion dose. Using secondary neutral mass spectrometry (SNMS), the sputtering yield of ruthenium was observed to decrease following ion bombardment by argon, xenon, and neon. High-detection-efficiency time-of-flight mass spectrometry was coupled with nonresonant laser ionization to allow real-time sputtering yield measurements and to minimize target damage during data collection. The experiments show that the sputtering yield of Ru(0001) decreases by 50%, following a primary ion fluence of, less than 10{sup 16} ions/cm{sup 2} for sputtering by either argon or neon ions and by 25%, following primary ion fluences of less than 10{sup 14} ions/cm{sup 2} for sputtering by xenon. The small size of the experimentally determined damage cross section suggests that microscopic changes in the surface structure cause the observed sputtering yield depression. In contrast to the ruthenium results, the sputtering yield of Al(111) appears to be insensitive to primary ion fluence at low fluences. Calculations using the TRansport of Ions in Matter (TRIM) Monte Carlo sputtering simulation were carried out to investigate the effect of primary ion implantation upon the sputtering yield of ruthenium as well as the effect of a reduced surface binding energy of ruthenium surface atoms. The TRIM results indicate that neither of these mechanisms can explain the experimentally observed fluence dependence of the sputtering yield of ruthenium.
In situ MeV ion beam analysis of ceramic surfaces modified by 100-400 keV ion irradiation
NASA Astrophysics Data System (ADS)
Yu, Ning; Levine, Timothy E.; Sickafus, Kurt E.; Nastasi, Michael; Mitchell, Jeremy N.; Maggiore, Carl J.; Evans, Caleb R.; Hollander, Mark G.; Tesmer, Joseph R.; Weber, William J.
This paper describes use of the in situ ion beam analysis facility developed at Los Alamos National Laboratory for the study of irradiation effects in ceramic materials. In this facility, an analytical beamline of 3 MV tandem accelerator and an irradiation beamline of 200 kV ion implanter are connected at 60 deg to a common target chamber. This facility provides a fast, efficient, and quantitative measurement tool to monitor changes of composition and crystallinity of materials irradiated by 100-400 keV ions, through sequential measurement of backscattering events of MeV ions combined with ion channeling techniques. We will describe the details of the in situ ion beam analysis and ion irradiation and discuss some of the important issues and their solutions associated with the in situ experiment. These issues include (1) the selection of axial ion channeling direction for the measurement of radiation damage; (2) surface charging and charge collection for data acquisition; (3) surface sputtering during ion irradiation; (4) the effects of MeV analytical beam on the materials; and (5) the sample heating effect on ion beam analysis.
In situ MeV ion beam analysis of ceramic surfaces modified by 100-400 keV ion irradiation
NASA Astrophysics Data System (ADS)
Yu, Ning; Levine, Timothy E.; Sickafus, Kurt E.; Nastasi, Michael; Mitchell, Jeremy N.; Maggiore, Carl J.; Evans, Caleb R.; Hollander, Mark G.; Tesmer, Joseph R.; Weber, William J.; Mayer, James W.
This paper describes the use of an in situ ion beam analysis facility developed at Los Alamos National Laboratory for the study of irradiation effects in ceramic materials. In this facility, an analytical beamline of 3 MV tandem accelerator and an irradiation beamline of 200 kV ion implanter are connected at 60° to a common target chamber. This facility provides a fast, efficient, and quantitative measurement tool to monitor changes of composition and crystallinity of materials irradiated by 100-400 keV ions through sequential measurement of backscattering events of MeV ions combined with ion channeling techniques. We will describe the details of the in situ ion beam analysis and ion irradiation and discuss some of the important issues and their solutions associated with the in situ experiment. These issues include (1) the selection of an axial ion channeling direction for the measurement of radiation damage; (2) sample surface charging and charge collection for data acquisition; (3) surface sputtering during ion irradiation; (4) the effects of MeV analytical beam on the materials; and (5) the sample heating effect on ion beam analysis.
Ion beam analysis of MgAl 2O 4 spinel irradiated with fast neutrons to 50–250 dpa
Ning Yu; Carl J. Maggiore; Kurt E. Sickafus; Michael Nastasi; Frank A. Garner; Glenn W. Hollenberg; Richard C. Bradt
Non-destructive ion beam analysis techniques have been employed to examine the radiation damage in MgAl204 spinel single crystals irradiated with fast neutrons at 400 and 750°C to high fluences (? 5 × 1022 n\\/cm2, En > 0.1 MeV). Rutherford backscattering and ion channeling measurements using 1–4 MeV He-ion beams revealed that the radiation damage saturated after irradiation at 400°C to
Oxygen diffusion and oxide phase formation in iron under swift heavy ion irradiation
Roller, Tobias; Bolse, Wolfgang [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)
While irradiating thin iron films deposited on silicon wafers with swift heavy ions in the energy range of a few MeV/amu, we have observed that the iron surface oxidizes due to the residual oxygen in the irradiation chamber, induced by the energy deposition by the ion. We have investigated these processes in detail using Rutherford backscattering spectrometry and conversion electron Moessbauer spectroscopy. We found that two different types of oxidation processes were active, depending on the electronic energy loss of the incident ions. Irradiations above the track formation threshold S{sub ec}{sup Fe} of iron resulted in diffusion-controlled dissolution of oxygen in the iron bulk. Below S{sub ec}{sup Fe}, but above the track formation threshold of iron oxide, chemical reaction and homogeneous oxide phase formation took place in a surface layer, while almost no oxygen diffusion into the iron bulk could be observed anymore. These phenomena are discussed in terms of the oxygen mobility in the excited ion tracks in iron and iron oxide. The effective diffusion constant estimated for swift heavy ion induced oxygen diffusion in iron is larger by a factor of 100-1000 than the one reported for thermally activated oxygen diffusion in molten iron.
Mechanisms of nanorod growth on focused-ion-beam-irradiated semiconductor surfaces: Role of redeposition
Wu, J. H.; Goldman, R. S.
We have examined the formation and evolution of irradiation-induced nanorod (NR) growth through a comparison of focused-ion-beam irradiation of InSb wafers and InSb/GaAs heterostructures. Above a critical ion dose, cone-shaped NRs capped with In islands form on both InSb surfaces. For InSb wafers, the NR base diameter increases with ion energy. In the case of InSb/GaAs heterostructures, as the milled depth approaches the InSb/GaAs interface, the cone-shaped NRs transition to capless NRs with a truncated cone shape. These results suggest a growth mechanism in which both the NR cap and body are supplied by redeposition of atoms sputtered from InSb.
Microstructural evolution of P92 ferritic/martensitic steel under argon ion irradiation
Jin, S.X. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, L.P., E-mail: email@example.com [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yang, Z.; Fu, D.J.; Liu, C.S. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Tang, R. [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chendu 610041 (China); Liu, F.H.; Qiao, Y.X.; Zhang, H.D. [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China)
Microstructural evolution of P92 ferritic/martensitic steel irradiated by Ar{sup +} ion beams at doses from 0.6 to 230 displacements per atom (dpa) at room temperature was investigated with conventional transmission electron microscope technique. Selected-area electron diffraction combined with bright-field and dark-field contrast image indicated that carbide/matrix interfaces were more easily damaged. The carbide peripheries became partly amorphous at irradiation dose of 2.3 dpa and were almost complete amorphous at the dose of 11.5 dpa. The small carbides would re-precipitate in matrices at 34.5 dpa. Energy dispersive X-ray analysis revealed that segregation of Cr and W and depletion of Fe in carbides occurred under irradiation. With the irradiation dose increasing, the irradiation induced segregation and depletion became more severe, which would influence mechanical properties of the steel. - Research Highlights: {yields} Carbide/matrix interfaces in P92 ferritic/martensitic steel were easily damaged. {yields} Small carbides re-precipitated in matrices after higher dose irradiation. {yields} Segregation of Cr and W and depletion of Fe in carbides occurred after irradiation.
DLTS study of deep level defects in Li-ion irradiated bipolar junction transistor
NASA Astrophysics Data System (ADS)
Madhu, K. V.; Kulkarni, S. R.; Ravindra, M.; Damle, R.
Commercial npn transistor (2N 2219A) irradiated with 50 MeV Li 3+-ions with fluences ranging from 3.1 × 10 13 ions cm -2 to 12.5 × 10 13 ions cm -2, is studied for radiation induced gain degradation and minority carrier trap levels or recombination centers. The properties such as activation energy, trap concentration and capture cross section of induced deep levels are studied by deep level transient spectroscopy (DLTS) technique. Minority carrier trap levels with energies ranging from 0.237 eV to 0.591 eV were observed in the base-collector junction of the transistor. In situ I- V measurements were made to study the gain degradation as a function of ion fluence. Ion induced energy levels result in increase in the base current through Shockley Read Hall (SRH) or multi-phonon recombination and subsequent transistor gain degradation.
Temporal evolution of nanoporous layer in off-normally ion irradiated GaSb
Datta, D. P.; Garg, S. K.; Som, T., E-mail: firstname.lastname@example.com [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Kanjilal, A. [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, Uttar Pradesh 203 207 (India); Sahoo, P. K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, Odisha (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)
Room temperature irradiation of GaSb by 60?keV Ar{sup +}-ions at an oblique incidence of 60° leads to simultaneous formation of a nanoporous layer and undulations at the interface with the underlying substrate. Interestingly, with increasing ion fluence, a gradual embedding of the dense nanoporous layer takes place below ridge-like structures (up to the fluence of 1?×?10{sup 17} ions cm{sup ?2}), which get extended to form a continuous layer (at fluences ?4?×?10{sup 17} ions cm{sup ?2}). Systematic compositional analyses reveal the co-existence of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} in the surface layer. The results are discussed in terms of a competition between ion-induced defect accumulation and re-deposition of sputtered atoms on the surface.
Visualising discrete structural transformations in germanium nanowires during ion beam irradiation and subsequent annealing
NASA Astrophysics Data System (ADS)
Kelly, Roisin A.; Holmes, Justin D.; Petkov, Nikolay
In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods.In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04513k
Temperature-Ramped 129Xe Spin-Exchange Optical Pumping
We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode 129Xe hyperpolarizer utilizing three key temperature regimes: (i) "hot"—where the 129Xe hyperpolarization rate is maximal, (ii) "warm"—where the 129Xe hyperpolarization approaches unity, and (iii) "cool"—where hyperpolarized 129Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ?1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized 129Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant ?SEOP of 62.5 ± 3.7 × 10–3 min–1 vs 29.9 ± 1.2 × 10–3 min–1) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading—corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ?3.1 × 105 and ?2.32 × 108 at the relevant fields for clinical imaging and HP 129Xe production of 3 T and 4 mT, respectively); moreover, the intercycle "dead" time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of 129Xe hyperpolarization or the experimental stability for automation—making this approach beneficial for improving the overall 129Xe production rate in clinical settings. PMID:25008290
Spectroscopic and TSDC analysis of 100 MeV Ag ion irradiated polyetherimide
NASA Astrophysics Data System (ADS)
Goyal, Geetika; Garg, Maneesha; Quamara, J. K.
The energetic heavy ion irradiation effects in polymers have drawn considerable attention for the application of polymers in radioactive environment. In the present paper, we report the Fourier transform infrared (FTIR) and UV-visible spectroscopic analysis and thermally stimulated depolarization current (TSDC) investigations in polyetherimide (PEI) samples (25 ?m) irradiated with 100 MeV Ag ion at different fluences (5.6×1010, 1.8×1011, 1.8×1012 ions/cm2). The FTIR spectra of irradiated samples show an overall decrease in the intensity of all the typical bands, whereas the UV-visible spectra show a hyperchromic and bathochromic shift attributed to the formation of new defect sites. The radiation induced dehydrogenation of the methyl pendent group, opening of imide rings and the formation of carbonyl radicals and unsaturated C = C bonds are the major conclusion drawn from the FTIR analysisE The TSDC spectra of pristine PEI comprises two current maxima termed as ?- and ?-peak with their respective locations around 80° and 190 °C. These are attributed to dipole-orientation and space charge relaxation, respectively. A significant effect of irradiation is observed on the whole TSDC spectrum. The ?-peak vanishes due to demerization of carbonyl groups. Enhancement in the ?-peak has been associated to the formation of new deep traps. Some new radiation induced relaxation processes have also been identified.
Effects of high energy Au-ion irradiation on the microstructure of diamond films
Chen, Shih-Show [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Information Technology and Mobile Communication, Taipei College of Maritime Technology, Tamsui, New-Taipei 251, Taiwan (China); Chen, Huang-Chin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wang, Wei-Cheng; Lin, I-Nan; Chang, Ching-Lin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Guo Jinghua [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a{sub 0} = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.
Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation
NASA Astrophysics Data System (ADS)
Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.
Ni3V bulk intermetallic compounds with ordered D022 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D022 structure of Ni3V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D022 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.
Formation of complex precursors of amino acids by irradiation of simulated interstellar media with heavy ions
NASA Astrophysics Data System (ADS)
Kobayashi, K.; Suzuki, N.; Taniuchi, T.; Kaneko, T.; Yoshida, S.
A wide variety of organic compounds have been detected in such extraterrestrial bodies as meteorites and comets Amino acids were identified in the extracts from Murchison meteorite and other carbonaceous chondrites It is hypothesized that these compounds are originally formed in ice mantles of interstellar dusts ISDs in molecular clouds by cosmic rays and ultraviolet light UV Formation of amino acid precursors by high energy protons or UV irradiation of simulated ISDs was reported by several groups The amino acid precursors were however not well-characterized We irradiated a frozen mixture of methanol ammonia and water with heavy ions to study possible organic compounds abiotically formed in molecular clouds by cosmic rays A mixture of methanol ammonia and water was irradiated with carbon beams 290 MeV u from a heavy ion accelerator HIMAC of National Institute of Radiological Sciences Japan Irradiation was performed either at room temperature liquid phase or at 77 K solid phase The products were characterized by gel filtration chromatography GFC FT-IR pyrolysis PY -GC MS etc Amino acids were analyzed by HPLC and GC MS after acid hydrolysis or the products Amino acids such as glycine and alanine were identified in the products in both the cases of liquid phase and solid phase irradiation Energy yields G-values of glycine were 0 014 liquid phase and 0 007 solid phase respectively Average molecular weights of the products were estimated as to 2300 in both the case Aromatic hydrocarbons N-containing heterocyclic
Amorphization kinetics of Zr(Cr,Fe)[sub 2] under ion irradiation
Motta, A.T. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Nuclear Engineering); Howe, L.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Labs.); Okamoto, P.R. (Argonne National Lab., IL (United States))
Thin foils of Zircaloy-4 were irradiated with 350 KeV [sup 40]Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300--650 K. The irradiation-induced amorphization of the intermetallic precipitates Zr (Cr; Fe)[sub 2] and Zr[sub 2] (Ni, Fe) was studied in-situ. For Zr (Cr, Fe)[sub 2] precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr[sub 2] (Ni,Fe) precipitates it was found that amorphization occurred at 550 and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in context of previous neutron and electron irradiations and likely amorphization mechanisms are proposed.
Amorphization kinetics of Zr(Cr,Fe){sub 2} under ion irradiation
Motta, A.T. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Nuclear Engineering; Howe, L.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Labs.; Okamoto, P.R. [Argonne National Lab., IL (United States)
Thin foils of Zircaloy-4 were irradiated with 350 KeV {sup 40}Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300--650 K. The irradiation-induced amorphization of the intermetallic precipitates Zr (Cr; Fe){sub 2} and Zr{sub 2} (Ni, Fe) was studied in-situ. For Zr (Cr, Fe){sub 2} precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr{sub 2} (Ni,Fe) precipitates it was found that amorphization occurred at 550 and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in context of previous neutron and electron irradiations and likely amorphization mechanisms are proposed.
Microstructure and Mechanical Properties of Ti3SiC2 Irradiated by Carbon Ions
NASA Astrophysics Data System (ADS)
Wang, Kun; Qi, Qiang; Cheng, Gui-Jun; Shi, Li-Qun
Thanks to its noteworthy mechanical properties, excellent damage tolerance and good thermal stability, the Ti3SiC2 ternary compound has attracted great concern and has been considered as a potential structural component material for the 4th generation of reactors (e.g., gas fast nuclear reactors) and future fusion reactors. The outstanding properties are due to the nanolamellar structure which imparts characteristics of both metals and ceramics to this material. In our work, Ti3SiC2 samples have been irradiated by C+ ions with a high fluence of 1.78 × 1017 ions/cm2 at a range of temperatures from 120°C-850°C. Subsequently, series of characterization techniques including synchrotron irradiation x-ray diffraction, scanning electron microscopy and nano-indentation are carried out to understand the changes of microstructure and mechanical properties. The composition exhibits high damage tolerant properties and a high recovery rate through the analysis, especially at high temperature. The minimum damage to an irradiated sample appears around 350°C in the temperature range 120°C-550°C. At a high irradiation temperature, a significant reduction in the damage can be achieved and an almost complete lack of damage compared with an un-irradiated sample is revealed at the temperature of 850°C.
Role of impact parameter in branching reactions: Chemical accelerator studies of the reaction Xe++CH4?XeCH3 ++H
Miller, G. D.; Strattan, L. W.; Hierl, Peter M.
Integral reaction cross sections and product velocity distributions have been measured for the ion–molecule reaction Xe+(CH4,H)XeCH3 + over the relative reactant translational energy range of 0.7–5.5 eV by chemical accelerator techniques...
Erosion of carbon fiber composites under high-fluence heavy ion irradiation
NASA Astrophysics Data System (ADS)
Andrianova, Natalya N.; Borisov, Anatoly M.; Mashkova, Eugenia S.; Virgiliev, Yury S.
The ion-induced erosion, determining by sputtering yield Y and surface evolution including structure and morphology changes of the modified surface layers, of two commercial carbon fiber composites (CFC) with different reinforcement - KUP-VM (1D) and Desna 4 (4D) have been studied under 30 keV Ar + high fluence ( ?t ˜ 10 18-10 20 ion/cm 2) irradiation in the temperature range from room temperature to 400 °C. Ion-induced erosion results in the changes of carbon fiber structure which depend on temperature and ion fluence. Monitoring of ion-induced structural changes using the temperature dependence of ion-induced electron emission yield has shown that for Desna 4 and KUP-VM at dynamic annealing temperature ?? ? 170 °? the transition takes place from disordering at T < Ta to recrystallization at T > Ta. The annealing temperature ?? is close to the one for polycrystalline graphites. Microscopy analysis has shown that at temperatures ? < Ta the etching of the fibers results in a formation of trough-like longitudinal cavities and hillocks. Irradiation at temperatures T > Ta leads to a crimped structure with the ribs perpendicular to fiber axis. After further sputtering of the crimps the fiber morphology is transformed to an isotropic globular structure. As a result the sputtering yield decreases for Desna 4 more than twice. This value is almost equal to that for KUP-VM, Desna 4, polycrystalline graphites and glassy carbons at room temperature.
Spectral studies on Ag 8+ ions irradiated LAHCl·H 2O and LAHBr·H 2O single crystals
NASA Astrophysics Data System (ADS)
Sangeetha, K.; Ramesh Babu, R.; Ramamurthi, K.; Prakash, Jai; Khan, S. A.
L-Arginine hydrochloride monohydrate and L-arginine hydrobromide monohydrate single crystals are irradiated by 100 MeV Ag 8+ swift heavy ions. The residual gases liberated from the irradiated samples are monitored as a function of ion fluence using quadrupole mass analyzer. The C 2H 3+, C 2H 2, N 2, CO, HCl and CO 2 are the dominant gases liberated. Fourier transform infrared spectra of irradiated crystals explain the breaking of bonds in a localized region of the crystals. The crystallinity of irradiated crystals is analyzed by powder X-ray diffractions.
Neon ion simulation of neutron induced irradiation growth in zirconium alloys
D. O. Northwood; R. A. Herring
Irradiation growth, a shape change in the absence of an applied stress, is one of the factors limiting the performance of\\u000a pressure tubes in CANDU-PHW (Canadian Deuterium Uranium-Pressurized Heavy Water) nuclear reactors. Irradiation growth has\\u000a been measured in zirconium, Zircaloy-2, Zr-2.5wt%Nb and ExCel alloy (Zr-Sn-Nb-Mo) specimens using neon ion bombardment to\\u000a simulate the reactor environment. This growth data is compared
Nanometer-scale tunnel formation in metallic glass by helium ion irradiation
Shao Lin [Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States); Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Gorman, Brian P. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States); Aitkaliyeva, Assel [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); David Theodore, N. [CHD-Fab, Freescale Semiconductor, Inc., Chandler, Arizona 85224 (United States); Xie Guoqiang [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)
We have shown that upon high fluence helium ion irradiation, metallic glass Cu{sub 50}Zr{sub 45}Ti{sub 5} becomes highly porous at the depth of the helium projected range. The resulting porous region is characterized by the formation of a tunnel like structure and self-linkage of nanometer size gas bubbles. Furthermore, the irradiation leads to the formation of nanometer size Cu{sub x}Zr{sub y} crystals that are randomly distributed. The results of this study indicate that the He-filled bubbles have attractive interactions and experience considerable mobility. Movement of the bubbles is believed to be assisted by ballistic collisions.
Tuning the hydrophobicity of mica surfaces by hyperthermal Ar ion irradiation
Keller, Adrian; Ogaki, Ryosuke; Bald, Ilko; Dong Mingdong; Kingshott, Peter [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Ny Munkegade, 8000 Aarhus C (Denmark); Fritzsche, Monika; Facsko, Stefan [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Besenbacher, Flemming [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Ny Munkegade, 8000 Aarhus C (Denmark); Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C (Denmark)
The hydrophobicity of surfaces has a strong influence on their interactions with biomolecules such as proteins. Therefore, for in vitro studies of bio-surface interactions model surfaces with tailored hydrophobicity are of utmost importance. Here, we present a method for tuning the hydrophobicity of atomically flat mica surfaces by hyperthermal Ar ion irradiation. Due to the sub-100 eV energies, only negligible roughening of the surface is observed at low ion fluences and also the chemical composition of the mica crystal remains almost undisturbed. However, the ion irradiation induces the preferential removal of the outermost layer of K{sup +} ions from the surface, leading to the exposure of the underlying aluminosilicate sheets which feature a large number of centers for C adsorption. The irradiated surface thus exhibits an enhanced chemical reactivity toward hydrocarbons, resulting in the adsorption of a thin hydrocarbon film from the environment. Aging these surfaces under ambient conditions leads to a continuous increase of their contact angle until a fully hydrophobic surface with a contact angle >80 deg. is obtained after a period of about 3 months. This method thus enables the fabrication of ultrasmooth biological model surfaces with precisely tailored hydrophobicity.
Irradiation-induced Ag-colloid formation in ion-exchanged soda-lime glass
NASA Astrophysics Data System (ADS)
Caccavale, F.; De Marchi, G.; Gonella, F.; Mazzoldi, P.; Meneghini, C.; Quaranta, A.; Arnold, G. W.; Battaglin, G.; Mattei, G.
Ion-exchanged glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1-20% AgNO 3 in NaNO 3, at temperatures varying from 320 to 350°C, and processing times of the order of a few minutes. Irradiations of exchanged samples were subsequently performed by using H +m, He +, N + ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 × 10 15 and 2 × 10 17 ions/cm 2. Most of the samples were treated at current densities lower than 2 ?A/cm 2, in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1-10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RBS), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.
Structures and field emission characteristics of ion irradiated silicon nanowire arrays.
Zhao, Fei; Deng, Jian-hua; Zhao, Dan-dan; Chen, Ke-fan; Cheng, Guo-an; Zheng, Rui-ting
Silicon nanowire (SiNW) arrays irradiated by energetic Si ions were fabricated by metal vapor vacuum arc (MEVVA) ion implantation method. Hetero-structure of amorphous/crystalline nanowire was formed in which structure of the implanted region on the top of the nanowires was amorphous while the structure of unimplanted region on the bottom remained crystal. Field emission (FE) properties of the SiNW arrays could be improved and modulated by different implantation doses. A low turn-on field of 4.63 V/microm was observed in the SiNWs irradiated by 21 keV Si ion with a dose of 7.86 x 10(16)/cm2, and the applied field for the emission current density reaching 100 microA/cm2 is only 5.52 V/microm. The main reason for the efficient emission is attributed to the formation of amorphous SiNWs and structure defects after implantation. The ion irradiated SiNWs after post-annealing at high temperature had better FE property due to eliminating the restrain effect to electrons. PMID:21137999
124Xe(n,?)125Xe and 124Xe(n,2n)123Xe measurements for National Ignition Facility
NASA Astrophysics Data System (ADS)
Bhike, Megha; Ludin, Nurin; Tornow, Werner
The cross section for the 124Xe(n,?)125Xe reaction has been measured for the first time for neutron energies above 100 keV. In addition, the 124Xe(n,2n)123Xe reaction has been studied between threshold and 14.8 MeV. The results of these measurements provide sensitive diagnostic tools for investigating properties of the inertial confinement fusion plasma in Deuterium-Tritium (DT) capsules at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory.
Evidence for ion irradiation induced dissociation and reconstruction of Si-H bonds in hydrogen-implanted silicon
Di, Z. F.; Wang, Y. Q.; Nastasi, M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Shao, L. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, Texas 77843 (United States); Lee, J. K. [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States); Theodore, N. D. [Analog and Mixed-Signal Technologies, Freescale Semiconductor Inc., Tempe, Arizona 85284 (United States)
We observe that H-related chemical bonds formed in H-implanted Si will evolve under subsequent ion irradiation. During ion irradiation hydrogen is inclined to dissociate from simple H-related defect complexes (i.e., VH{sub x} and IH{sub x}), diffuse, and attach to vacancy-type defects resulting in new platelet formation, which facilitate surface blistering after annealing, a process completely inhibited in the absence of ion irradiation. The understanding of our results provides insight into the structure and stability of hydrogen-related defects in silicon.
Irradiation induced dislocations and vacancy generation in single crystal yttria stabilized zirconia
Jill Noel Johnsen
A determination of the most effective method of introducing defect clusters and forming nanocrystals in single crystal Yttria Stabilized Zirconia (YSZ) to increase its oxygen ion conductivity for use in solid oxide fuel cell has been investigated using several techniques. High-energy particle irradiation using 800 keV electrons and 20 MeV protons and Ar+ and Xe ++ ion implantation promote the
Glass carbon surface modified by the fluorine ion irradiation
NASA Astrophysics Data System (ADS)
Teranishi, Yoshikazu; Ishizuka, Masanori; Kobayashi, Tomohiro; Nakamura, Isao; Uematu, Takahiko; Yasuda, Takeshi; Mitsuo, Atsushi; Morikawa, Kazuo
Application of nano and micro fabrication techniques in industry requires solution to some crucial problems. One of the significant problems is the sticking interface between mold surface and imprinted polymer. In this study, we report a solution to the sticking interface problem by modification of nano imprinting mold using fluorine ion implantation. After the fluorine implantation, anti sticking layer appeared on the nano imprinting mold surface. After the implantation, a mold made from glass like carbon was patterned by focused ion beam lithography. The pattern was made up of word "TIRI". The line width was varied with 300 nm, 500 nm, and 1 ?m. The line depth was about 200 ˜ 300 nm. The average depth of implanted fluorine was approximately 90 nm. After imprinting, the resin was removed from the mold by mechanical lift-off process. Transferred pattern was observed and confirmed by a scanning electron microscope (SEM) and an atomic force microscope (AFM). The pattern transferred from mold to resin was found to be successful.
Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition
Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino
Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 nm ({approx}220 {micro}g/cm{sup 2}) Tm{sub 2}O{sub 3} target, and an RMS roughness of 2.0 nm after irradiation was measured by atomic force microscopy (AFM). Scanning electron microscopy of the irradiated target reveals no significant differences in surface homogeneity when compared to imaging prior to irradiation. Target flaking was not observed from monitoring Rutherford scattered particles as a function of time.
126Xe Anomaly in Lunar Regolith Samples: A Possible Explanation
NASA Astrophysics Data System (ADS)
Begemann, F.; Mathew, K. J.
Lunar regolith samples exposed to solar radiation have been extensively studied to obtain the isotopic composition of the solar noble gases implanted into them [1, 2]. Regolithic Xe in these samples has been shown to be a mixture of a primary solar wind component with components produced in situ by cosmic ray spallation, by neutron capture reactions on I, and also by decay of extinct radionuclides (cf. e.g. [3]). In addition an essentially monoisotopic contribution at 126Xe has been observed to be present in at least some samples, its relative proportion varying from sample to sample [3]. A possible origin of this excess from the reaction 127I(n,2n)126I, followed by beta- -decay to 126Xe was suggested [3] but after considering the required iodine abundances this mechanism of production was argued against. We propose that the low energy proton reaction with Te, viz. 126Te(p,n)126I(beta-,gamma)126Xe could explain this anomaly. Since the threshold for this reaction is low (< 3 MeV) the abundant low energy protons on the lunar surface might be able to account for this anomaly. Moreover, because the same reaction on 128Te will produce 128Xe this might also account for the "rough correlation between excess 126Xe and excess 128Xe" [3]. According to available cross section data for proton energies between 10 MeV and 20 MeV the production ratio 126Xe/128Xe from (p,n)-reactions acting on natural Te is 0.8 which translates into a ratio delta 126Xe/ delta 128Xe of about 16. In order to look into the feasibility of this reaction to explain the size of the 126Xe anomaly we have irradiated Te targets with 4, 10, 14, and 17 MeV protons. Data will be presented for the cross sections that will allow to estimate whether the product (proton dose x tellurium content x cross section) yields the observed excesses. References: [1] Wieler R. et al. (1986) GCA, 50, 1997-2017. [2] Benkert J.-P. et al. (1993) JGR Planets, 98, 13147-13162. [3] Pepin R. O. et al. (1995) GCA, submitted.
Wear resistance of the ion-modified surface of zirconium-alloy tubes irradiated by He + and Ar + ion beams with wide energy spectra
B. A. Kalin; N. V. Volkov; E. A. Anan'eva
The results of investigating the wear resistance of E110 alloy samples irradiated by a He+ + Ar+ beam with a wide energy spectrum are presented. Surface modification under irradiation by an Ar+ beam at doses higher than 2 × 1018 ion\\/cm2 is shown to cause substantial enhancement of the wear resistance of samples because the structural homogeneity of near surface
Alkali-ion irradiated alpha-quartz: low-temperature cathodoluminescence after chemical epitaxy
NASA Astrophysics Data System (ADS)
Lieb, K.-P.; Gasiorek, S.; Keinonen, J.; Sahoo, P.-K.; Sajavaara, T.
Even small fluences of implanted ions used for opto-doping alpha-quartz lead to amorphization of the matrix, but subsequent annealing in air or oxygen can restore its crystalline order (chemical epitaxy). Here we report on cathodoluminescence (CL) spectroscopy during chemical epitaxy of alpha-quartz irradiated with 50-keV Na-ions or 175-keV Rb ions and annealed in 18O2-gas. In particular, the variation of the CL spectra with the ion fluence will be discussed. The CL spectra at 10 K show an intense 2.90-2.95 eV blue band and differ greatly from the ones taken at 300 K. Finally we report on the observation of a spider-web surface structure after Rb implantation and annealing in lowpressure oxygen.
The real structure of columnar pinning centers in heavy-ion-irradiated cuprate superconductors
Welch, D.O.; Zhu, Y. [Brookhaven National Lab., Upton, NY (United States); Budhani, R.C. [Indian Institute of Technology Kanpur (India). Dept. of Physics
There has been considerable recent interest in the use of columnar defects produced by irradiation with energetic heavy ions to raise the irreversibility line and improve the critical current density of cuprate superconductors. In the interpretation and theoretical modeling of the flux-pinning characteristics of heavy-ion tracks, it is generally assumed that they are simply columns of non-superconducting material. In this paper we present a more realistic description, based both on resistivity measurements and on detailed, quantitative transmission electron microscope methods (both imaging and analytical studies), of the nature of heavy-ion damage, including defects, disorder, strain fields, and oxygen deficiencies in the matrix of the superconductor surrounding the amorphous columns. The presence of such disorder appears to be a consequence of the mechanism of track formation, which involves partial epitaxial regrowth of a molten region which follows the passage of sufficiently energetic ions.
Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO{sub 2}
Kluth, P.; Giulian, R.; Ridgway, M. C. [Department of Electronic Materials Engineering, Australian National University, Canberra ACT 0200 (Australia); Pakarinen, O. H.; Djurabekova, F.; Nordlund, K. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki (Finland); Byrne, A. P. [Department of Nuclear Physics, Australian National University, Canberra ACT 0200 (Australia)
We report on the observation of nanoscale density fluctuations in 2 {mu}m thick amorphous SiO{sub 2} layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5 x 10{sup 12} ions/cm{sup 2}, where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track ''annihilation'' process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.
Irradiation of water ices by 2 keV carbon ions
NASA Astrophysics Data System (ADS)
Hunniford, C. A.; Dawes, A.; Fulvio, D.; Sivaraman, B.; Merrigan, T. L.; McCullough, R. W.; Mason, N. J.; Palumbo, M. E.
In this paper, we report on the results of experimental studies of the irradiation of pure water ices using 2 keV 13C+ and 13C2+ ions. Studies have been carried out at two temperatures (30 and 90 K) and the influence of the different morphologies at these temperatures has also been studied. With singly charged ions, the formation of 13CO2 was observed to be a strongly dependent upon morphology and showed a weaker dependence upon temperature. With doubly charged ions, the dependence upon temperature was significantly stronger. This is explained by enhanced production of reactive species resulting from the additional potential energy contained within the doubly charged ions. Increased temperature provides mobility to these species which may then yield additional 13CO2.
Chemi-luminescence measurements of hyperthermal Xe{sup +}/Xe{sup 2+}+ NH{sub 3} reactions
Prince, Benjamin D.; Steiner, Colby P. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States); Chiu, Yu-Hui [Busek Co. Inc, Natick, Massachusetts 01760 (United States)
Luminescence spectra are recorded for the reactions of Xe{sup +}+ NH{sub 3} and Xe{sup 2+}+ NH{sub 3} at energies ranging from 11.5 to 206 eV in the center-of-mass (E{sub cm}) frame. Intense features of the luminescence spectra are attributed to the NH (A {sup 3}{Pi}{sub i}-X {sup 3}{Sigma}{sup -}), hydrogen Balmer series, and Xe I emission observable for both primary ions. Evidence for charge transfer products is only found through Xe I emission for both primary ions and NH{sup +} emission for Xe{sup 2+} primary ions. For both primary ions, the absolute NH (A-X) cross section increases with collision energy before leveling off at a constant value, approximately 9 x 10{sup -18} cm{sup 2}, at about 50 eV while H-{alpha} emission increases linearly with collision energy. The nascent NH (A) populations derived from the spectral analysis are found to be independent of collision energy and have a constant rotational temperature of 4200 K.
Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow
Scott A. Norris
We present a model for the effect of stress on thin amorphous films that develop atop ion-irradiated silicon, based on the mechanism of ion-induced anisotropic plastic flow. Using only parameters directly measured or known to high accuracy, the model exhibits remarkably good agreement with the wavelengths of experimentally-observed patterns, and agrees qualitatively with limited data on ripple propagation speed. The predictions of the model are discussed in the context of other mechanisms recently theorized to explain the wavelengths, including extensive comparison with an alternate model of stress.
Response of Nanocrystalline 3C Silicon Carbide to Heavy-Ion Irradiation
Jiang, Weilin; Wang, Haiyan; Kim, Ickchan; Bae, In-Tae; Li, Guosheng; Nachimuthu, Ponnusamy; Zhu, Zihua; Zhang, Yanwen; Weber, William J.
Nanostructured materials are generally believed to be more radiation resistant. This study reports on Au ion induced amorphization in nanocrystalline 3C-SiC, characterized using x-ray diffraction, transmission electron microscopy and Raman spectroscopy. Full amorphization at room temperature occurs at a comparable dose to that for bulk SiC single crystals. The behavior is attributed to a high ion flux and sluggish migration of point defects produced during irradiation. The results may have a significant implication of using nanophased SiC in extremely high radiation environments.
The influence of N-ion irradiation on superconducting TiN
Thompson, J.R.; Ellis, J.T.; Christen, D.K.; Sekula, S.T.; Lewis, J.D.; Williams, J.M.
The influence of disorder on the properties of the B1 phase superconductive compound titanium nitride has been investigated. Following synthesis and characterization of thin films of TiN, the materials were disordered progressively and uniformly by irradiation with nitrogen ions. The superconducting transition temperature T/sub c/ decreased and the low temperature electrical resistivity rho increased as lattice damage was introduced. The dependence of both T/sub c/ and rho on N-ion fluence phi could be described by exponentially saturating functions of phi with similar rate constants. These constants correspond to characteristic damage energy densities of 14 and 12 eV/atom, respectively.
Temporal stability of Y Ba Cu O nano Josephson junctions from ion irradiation
Cybart, Shane A.; Roediger, Peter; Chen, Ke; Parker, J. M.; Cho, Ethan Y.; Wong, Travis J.; Dynes, R. C.
We investigate the temporal stability of YBa2Cu3O7 Josephson junctions created by ion irradiation through a nano-scale implant mask fabricated using electron beam lithography and reactive ion etching. A comparison of current-voltage characteristics measured for junctions after fabrication and eight years of storage at room temperature show a slight decrease in critical current and increase in normal state resistance consistent with broadening of the weaklink from diffusion of defects. Shapiro step measurements performed 8 years after fabrication reveal that device uniformity is maintained and is strong evidence that these devices have excellent temporal stability for applications.
Effect of low energy ion irradiation on CdTe crystals: Luminescence enhancement
Olvera, J.; Plaza, J. L.; Dios, S. de; Dieguez, E. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O.; Avella, M. [Departamento Fisica Materia Condensada, GdS-Optronlab Group, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain)
In this work we show that low energy ion sputtering is a very efficient technique as a cleaning process for CdTe substrates. We demonstrate, by using several techniques like grazing-angle x-ray diffraction, cathodoluminescence, microluminescence, and micro-Raman spectroscopy that the luminescent properties of CdTe substrates can be very much increased when CdTe surfaces are irradiated with low energy Argon ions. We postulate that this enhancement is mainly due to the removal of surface damage induced by the cutting and polishing processes. The formation of a low density of nonluminescent aggregates after the sputtering process has also been observed.
The effect of lattice and grain boundary diffusion on the redistribution of Xe in metallic nuclear fuels: Implications for the use of ion implantation to study fission-gas-bubble nucleation mechanisms
Wayne E. King; Scott J. Tumey; Jeffrey Rest; George H. Gilmer
A multi-atom gas bubble-nucleation mechanism has been proposed as part of a predictive fission-gas release model for metallic nuclear fuels. Validation of this mechanism requires experimental measurement of fission-gas bubble-size distributions at well-controlled gas concentrations and temperatures. There are advantages to carrying out such a study using ion implantation as the source of gas atoms compared with neutron irradiations. In
The first narrow-band XeCl-excilamp application for complex psoriasis curing
NASA Astrophysics Data System (ADS)
Dmitruck, Vadim S.; Sosnin, Edward A.; Obgol'tz, Irina A.
Clinical efficiency estimation of XeCl-excilamp application for psoriasis curing in comparison with other methods of phototherapy for has been carried out for the first time. Curing psoriasis by XeCl-excilamp assistance is shown to be an effective and present-date method. Such a phototherapy advantages suggested are the good tolerance, and absence of intact skin irradiation. The use of chemicals is no longer relevant, and the total doze of irradiation happens to be rather low.
Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions
Jiang, Weilin; Wang, Haiyan; Kim, Ickchan; Zhang, Yanwen; Weber, William J.
Irradiation induced amorphization in nanocrystalline and single crystal 3C-SiC has been studied using 1 MeV Si+ ions under the identical irradiation conditions at room temperature and 400 K. The disordering behavior has been characterized using in-situ ion channeling and ex-situ x-ray diffraction methods. The results show that, compared to single crystal 3C-SiC, full amorphization of small 3C-SiC grains (~3.8 nm in size) occurs at a slightly lower dose at room temperature. For grains with sizes of 3.0 - 3.8 nm, the amorphization dose is lower at room temperature than 400 K. A significantly lower dose for amorphization of smaller grains (2.0 nm in size) is observed at 400 K. The behavior has been interpreted based on the competition between the interface and interior amorphization.
Application of positron beam Doppler broadening technique to ion beam irradiation in nickel
NASA Astrophysics Data System (ADS)
Iwai, Takeo; Tsuchida, Hidetsugu; Awano, Misa
The formation processes of vacancy-type defects induced by ion irradiation in nickel were investigated with a variable-energy positron beam Doppler broadening technique in order to find the appropriate experimental condition for in situ positron beam experiments. Nickel ion irradiation at 300-343 K induces an S parameter increase, but the dependence of the S parameter on positron energy is very similar to that of cold-rolled nickel, which suggests positron trapping by small vacancy-type defects such as SFTs. The best experimental condition for investigation of cavity nucleation process by in situ positron beam Doppler experiments is suggested to be around 0.1-0.4 dpa at 773 K.
Radiation damage and deuterium trapping in deuterium ion irradiated austenitic stainless steel
NASA Astrophysics Data System (ADS)
Yoshida, N.; Ashizuka, N.; Fujiwara, T.; Kurita, T.; Muroga, T.
The nature of radiation-induced defects and their roles in deuterium trapping in deuterium-ion-irradiated austenitic stainless steel, JPCA2, were studied by the complementary use of transmission electron microscopy (TEM) and thermal desorption spectroscopy (TDS). By irradiation with deuterium ions of keV energy at room temperature, very small dislocation loops and platelet-like deuterium clusters were formed. The comparison of the results of TEM and TDS showed that deuterium atoms trapped by the dislocation loops and by deuterium clusters dissociated at around 220°C and 300°C, respectively. Major trapping sites in JPCA2 are radiation-induced point defect clusters and some kind of imperfection in the matrix. Most of the deuterium atoms trapped by these sites are released at relatively low temperatures (< 180°C).
Evidence of extended defects in pure zirconia irradiated by swift heavy ions
Baldinozzi, Gianguido [SPMS, UMR CNRS 8580, Ecole Centrale Paris, 92295 Chatenay-Malabry (France); DEN/DMN/SRMA/LA2M, CEA Saclay, 91191 Gif-sur-Yvette (France); Simeone, David; Gosset, Dominique [DEN/DMN/SRMA/LA2M, CEA Saclay, 91191 Gif-sur-Yvette (France); SPMS, UMR CNRS 8580, Ecole Centrale Paris, 92295 Chatenay-Malabry (France); Monnet, Isabelle [CIRIL, CEA-CNRS-ENSICAEN, 14070 Caen Cedex 5 (France); Le Caeer, Sophie [DSM/DRECAM/SCM/URA 331 CNRS, CEA Saclay, 91191 Gif sur Yvette (France); Mazerolles, Leo [CECM, UPR CNRS 2801, 94407 Vitry sur Seine (France)
X-ray diffraction, transmission electron microscopy, and optical spectroscopy were used to investigate the microstructure of polycrystalline samples of pure monoclinic zirconia irradiated by high energy ions. These techniques point out the existence of extended defects and they allow to monitor the tetragonal to monoclinic phase transition as a function of the temperature during isochronal annealings. The Landau theory approach explains the phase transition mechanism via the presence of an important strain field induced by dislocations. Though high and low energy ions can effectively stabilize the same tetragonal phase in the irradiated layer, only point defects are produced at low energy whereas extended defects are also observed at high energy, showing the strong influence of the energy deposition modes on the observed microstructures.
Outgassing and degradation of polyimide induced by swift heavy ion irradiation at cryogenic temperature
Severin, D. [Department of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); GSI-Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany); Balanzat, E. [CIMAP-CIRIL, CEA-CNRS-ENSICAEN, 14050 Caen cedex 4 (France); Ensinger, W. [Department of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Trautmann, C. [GSI-Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany)
Polyimide foils were irradiated with energetic Kr (740 MeV) and Pb (890 MeV) ions at cryogenic temperature (12 K). Beam-induced degradation processes were monitored by residual gas analysis and online infrared spectroscopy. The outgassing components observed at low irradiation temperatures differ in quantity but are similar in mass distribution to those identified at room temperature exposure. Besides CO as major volatile fragment, a significant contribution of short hydrocarbons like C{sub 2}H{sub x} is released. In situ infrared spectroscopy indicates accumulation of CO and CO{sub 2} molecules at 12 K in the foils. During heat-up cycles, most of these frozen gases become mobile and outgas at a temperature between 35 and 55 K. The study is motivated by the application of polyimide foils as insulating material in high radiation environment of the future accelerator facility for antiproton and ion research (FAIR).
Direct observations of the primary state of radiation damage of ion-irradiated tungsten and platinum
Seidman, D. N.; Current, M. I.; Pramanik, D.; Wei, C. Y.
A brief summary was presented of all the Cornell work on the primary state of radiation damage in ion-irradiated tungsten and platinum. The primary research tool for all this research was the field-ion microscope (FIM); the FIM was ideally suited for this research because of its excellent atomic resolution and the ability to examine the interior of the specimens, as a result of the field-evaporation effect. This paper summarized, in outline form, the following items: (1) the principal experimental quantities determined from the analyses performed on all the individual depleted zones (DZs) observed; (2) the main experimental programs; (3) a number of the more important results and conclusions concerning the vacancy structure of DZs; and (4) the three-dimensional spatial distribution of self-interstitial atoms around DZs in tungsten which had been irradiated and examined in situ at 10/sup 0/K.
Nanostructured Cu/Nb multilayers subjected to helium ion-irradiation
NASA Astrophysics Data System (ADS)
Zhang, X.; Li, Nan; Anderoglu, O.; Wang, H.; Swadener, J. G.; Höchbauer, T.; Misra, A.; Hoagland, R. G.
Helium ion-irradiation experiments have been performed in single layer Cu films, Nb films and Cu/Nb multilayer films with layer thickness varying from 2.5 nm to 100 nm each layer. Peak helium concentration approaches a few atomic percent with 6-9 displacement-per-atom in Cu and Nb. He bubbles were observed in single layer Cu and Nb films, as well as in Cu 100 nm/Nb 100 nm multilayers with helium bubbles aligned along layer interfaces. Helium bubbles are not resolved via transmission electron microscopy in Cu 2.5 nm/Nb 2.5 nm multilayers. These studies indicate that layer interface may play an important role in annihilating ion-irradiation induced defects such as vacancies and interstitials and have implications in improving the radiation tolerance of metallic materials using nanostructured multilayers.
Ar ions irradiation effects in ZrN thin films grown by pulsed laser deposition
NASA Astrophysics Data System (ADS)
Craciun, D.; Socol, G.; Dorcioman, G.; Simeone, D.; Gosset, D.; Behdad, S.; Boesl, B.; Craciun, V.
Thin ZrN films (<500 nm) were grown on (1 0 0)Si substrates at a substrate temperature of 500 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under CH4 or N2 atmosphere. Glancing incidence X-ray diffraction showed that films were nanocrystalline, while X-ray reflectivity studies indicated that the films were very dense and with a smooth surface. The films were used to study the effect of 800 keV Ar ion irradiation on their structure and properties. After irradiation with a dose of 1014 at/cm2 the lattice parameter and crystallites size did marginally change. However, after irradiation with a 1015 at/cm2 dose, a clear increase in the lattice parameter accompanied by a significant decrease in nanohardness and Young modulus were observed.
Increasing the Stiffness of SWCNT Bucky Paper by Heavy Ion Irradiation
NASA Astrophysics Data System (ADS)
Salmi, Ari; Hæggström, Edward; Arstila, Kai; Nordlund, Kai; Keinonen, Juhani
We verify simulation results indicating that carbon ion irradiation increases the stiffness of single wall carbon nanotube bucky paper (SWCNT). 4 MHz longitudinal and 15 MHz shear ultrasonic signals were transmitted by means of dry-coupled acoustic horns through 40±4 ?m thick samples and the time-of-flight (TOF) through the samples was measured. From the TOF the velocity of the wave was determined and the out-of-plane elastic and shear moduli were calculated. The nonlinearity parameter B/A for the irradiated and reference sample was measured. The results indicated a significant increase both in the shear modulus (90 %) and in the longitudinal modulus (69 %) for certain irradiation doses as predicted by simulations. In addition, a 36% increase in the acoustic nonlinearity parameter (B/A) was observed. The investigated fluence range was 1?1013 to 3?1014 cm-2.
Superiority of ion irradiation over annealing for enhancing the thermopower of PbTe thin films
NASA Astrophysics Data System (ADS)
Gupta, Srashti; Agarwal, D. C.; Tripathi, S. K.; Neeleshwar, S.; Panigrahi, B. K.; Jacquot, A.; Lenoir, B.; Avasthi, D. K.
Present study reveals that swift heavy ion (SHI) irradiation enhances thermoelectric properties and the annealing deteriorates thermoelectric performance of PbTe thin film. X-ray diffraction (XRD), Atomic force microscopy (AFM) and Rutherford backscattering spectrometry (RBS) measurements are performed for phase formation, surface morphology and elemental composition of all the samples, respectively. Electrical conductivity (?) and thermo power (S) measurement of all the samples have also been measured using four probe method. The increase in thermo power (S) is ˜40% upto high temperature (˜520 K) after irradiation whereas it decreases on annealing treatment. These findings are discussed on the basis of density of states enhancement or carrier scattering due to the point defects after SHI irradiation.
Disordering and dissolution of [gamma][prime] precipitates under ion irradiation
Bourdeau, F.; Camus, E.; Abromeit, C.; Wollenberger, H. (Hahn-Meitner-Institut Berlin GmbH, Glienicker Stragese 100, D-14109 Berlin (Germany))
The stability of the [gamma][prime] phase of the nickel-base alloy Nimonic PE16 under irradiation with Ni[sup +] ions of 300-keV energy is studied by means of transmission electron microscopy. The disordering of the [gamma][prime] phase could be followed as a function of fluence. The main finding is the observation of weak but measurable superlattice reflections between 0.1 and 1 dpa after irradiation at room temperature. The superlattice reflections disappear in two steps. Their intensities decrease considerably within a fluence of 0.1 dpa, while weak intensities are observed up to a fluence of 1 dpa. These reflections disappear completely after a fluence of 2 dpa. The results are discussed within a model which considers both disordering and dissolution of precipitates under cascade producing irradiation.
Evolution of microstructure and crack pattern in NiO thin films under 200 MeV Au ion irradiation
NASA Astrophysics Data System (ADS)
Mallick, P.; Agarwal, D. C.; Rath, Chandana; Behera, D.; Avasthi, D. K.; Kanjilal, D.; Mishra, N. C.
NiO thin films grown on Si (100) substrate by electron beam evaporation method and sintered at 700 °C were irradiated with 200 MeV Au15+ ions. The fcc structure of the sintered films was retained up to the highest fluence (1×1013 ions cm-2) of irradiation. However the microstructure of the pristine film underwent a considerable modification with increasing ion fluence. 200 MeV Au ion irradiation led to compressive stress generation in NiO medium. The diameter of the stressed region created by 200 MeV Au ions along the ion path was estimated from the variation of stress with ion fluence and found to be ˜11.6 nm. The film surface started cracking when irradiated at and above the fluence of 3×1012 ions cm-2. Ratio of the fractal dimension of the cracked surface obtained at 200 MeV and 120 MeV (Mallick et al., 2010a) Au ions was compared with the ratio of the radii of ion tracks calculated based on Coulomb explosion and thermal spike models. This comparison indicated applicability of thermal spike model for crack formation.
Heavy ion irradiation on conducting polypyrrole and ZrO 2–polypyrrole nanocomposites
Amitabha De; Ajay Das; Susanta Lahiri
Heavy ion irradiation on conducting polypyrrole (PPy) and ZrO2–polypyrrole (ZrO2–PPy) nanocomposites were carried out with an aim to illustrate the suitability of these materials for use in various space probes where they might be exposed to different cosmic radiations. Polypyrrole and ZrO2–polypyrrole nanocomposite samples were prepared from aqueous solution of pyrrole and pyrrole suspended in colloidal dispersion of ZrO2, respectively,
Adsorption of Uranyl Ions into Poly(Acrylamide?co?Acrylic Acid) Hydrogels Prepared by Gamma Irradiation
Dilek ?olpan; Olgun Güven
Acrylamide (AAm)\\/Acrylic Acid (AAc) copolymers have been prepared by gamma irradiation of binary mixtures at three different compositions where the acrylamide\\/acrylic acid mole ratios varied around 15, 20, and 30%. Threshold dose for 100% conversion of monomers into hydrogels was found to be 8.0 kGy. Poly(Acrylamide?co?Acrylic Acid) (poly(AAm?co?AAc)) hydrogels have been considered for the removal of uranyl ions from aqueous solutions.
Strengthening of alumina by reactions with silicon film on the surface and effects of ion irradiation
Noda, S.; Doi, H.; Hioki, T.; Kawamoto, J.I.; Kamigaito, O.
Deposition of Si film on sintered alumina, followed by annealing at 1673 K in air, increased the flexural strength by approx. = 28%. Mullite formation on the surface was confirmed by X-ray diffraction analysis. Ion irradiation of the Si/alumina interface, followed by annealing, produced anorthite but not mullite, and the flexural strength also increased by approx. = 35%. Thermal expansion mismatch between surface compounds and the alumina body may be responsible for the strengthening.
Disorder accumulation and recovery in gold-ion irradiated 3C-SiC
W. Jiang; W. J. Weber; J. Lian; N. M. Kalkhoran
A single-crystal 3C-SiC film on a Si\\/SiO2\\/Si (separation by implantation of oxygen ) substrate was irradiated in different areas at 156 K with Au2+ ions to low fluences. The disorder profiles as a function of dose on both the Si and C sublattices have been determined in situ using a combination of 0.94 MeV D+ Rutherford backscattering spectrometry and nuclear
Photoelectron spectroscopy of ion-irradiated B-doped CVD diamond surfaces
G. Francz; P. Reinke; P. Oelhafen; W. Hänni
Chemical vapour deposition (CVD) diamond films were irradiated by 1 keV argon ions at room temperature with doses ranging from 3.6 × 1012 to 1.1 × 1016 Ar+ cm2. The influence of sputtering on the valence band density of states of a boron-doped CVD diamond film was investigated by ultraviolet photoelectron spectroscopy and the changes in the plasmon features were
Deuterium retention and near-surface modification of ion-irradiated diamond exposed to fusion-relevant plasma
NASA Astrophysics Data System (ADS)
Deslandes, Alec; Guenette, Mathew C.; Corr, Cormac S.; Karatchevtseva, Inna; Thomsen, Lars; Lumpkin, Gregory R.; Riley, Daniel P.
Chemical vapour deposited diamond was irradiated with 5 MeV carbon ions to simulate the damage caused by collision cascades from neutron irradiation in a fusion environment. Ion-irradiated samples were then exposed to a deuterium plasma in MAGPIE with ion flux of ˜1.3 × 1021 ions m-2 s-1. Raman and near edge x-ray absorption fine structure (NEXAFS) spectroscopy were used to characterize the degree of disorder and sp2-bonding induced by the ion irradiation. The signals of sp2-bonded and disordered carbon were observed to decrease after exposure to the deuterium plasma, although sharp Raman peaks indicative of vacancy and interstitial defects induced by the MeV ions were less affected. Recovery of a diamond-like surface after plasma exposure was evident in the NEXAFS spectra. Elastic recoil detection analysis showed that the ion-damaged diamond retained more deuterium than diamond exposed only to deuterium plasma. For the case of unirradiated samples, diamond retained more deuterium than graphite. However, for the case of the ion-irradiated samples, diamond exhibited less deuterium retention than graphite.
In Situ TEM Concurrent and Successive Au Self-Ion Irradiation and He Implantation
Chisholm, Claire [University of California, Berkeley & LBNL] [University of California, Berkeley & LBNL; Hattar, K [Sandia National Laboratories (SNL)] [Sandia National Laboratories (SNL); Minor, Andrew [University of California, Berkeley & LBNL] [University of California, Berkeley & LBNL
The development of advanced computational methods used for predicting performance lifetimes of materials exposed to harsh radiation environments are highly dependent on fundamental understanding of solid-radiation interactions that occur within metal components. In this work, we present successive and concurrent in situ TEM dual-beam self-ion irradiation of 2.8MeV Au4+ and implantation of 10 keV He1+, utilizing a new facility at Sandia National Laboratories. These experiments, using a model material system, provide direct real-time insight into initial interactions of displacement damage and fission products that simulate damage from neutron exposure. In successive irradiation, extensive dislocation loop and stacking fault tetrahedra damage was formed and could be associated with individual ion strikes, but no evidence of cavity formation was observed. In contrast, concurrent irradiation to the same dose resulted in the onset of cavity formation at the site of a heavy-ion strike. This direct real-time observation provides insight into the complex interplay between the helium and vacancy dynamics.
Ion-irradiation-induced preferential amorphization of Ge nanocrystals in silica
NASA Astrophysics Data System (ADS)
Ridgway, M. C.; Azevedo, G. De M.; Elliman, R. G.; Glover, C. J.; Llewellyn, D. J.; Miller, R.; Wesch, W.; Foran, G. J.; Hansen, J.; Nylandsted-Larsen, A.
Extended x-ray absorption fine structure (EXAFS) measurements have been used to characterize the ion-irradiation-induced crystalline-to-amorphous phase transformation in Ge nanocrystals. The atomic-scale structure of Ge nanocrystals in a silica matrix is first shown to deviate from that of bulk crystalline material with an increase in both Gaussian and non-Gaussian forms of structural disorder. The magnitude of the disorder in the bond-length distribution is comparable to that of relaxed amorphous Ge. The amorphization of such nanocrystals is then demonstrated at an ion dose ˜100 times less than that required for bulk crystalline material irradiated simultaneously. Specifically, Ge nanocrystals irradiated at -196°C are rendered amorphous at ˜0.01 displacements per atom. Finally, we show the atomic-scale structure of amorphized nanocrystals and bulk amorphous material is comparable. The rapid amorphization of Ge nanocrystals is potentially the result of several factors including (i) the preferential nucleation of the amorphous phase at the nanocrystal/matrix interface, (ii) the preirradiation, higher-energy structural state of the nanocrystals themselves, (iii) an enhanced vacancy concentration within the nanocrystals due to inhibited Frenkel pair recombination when Ge interstitials are recoiled into the matrix, and (iv) ion-beam mixing and the subsequent increase in nanocrystal impurity concentrations.
Void swelling in high dose ion-irradiated reduced activation ferritic-martensitic steels
NASA Astrophysics Data System (ADS)
Wang, Xu; Monterrosa, Anthony M.; Zhang, Feifei; Huang, Hao; Yan, Qingzhi; Jiao, Zhijie; Was, Gary S.; Wang, Lumin
To determine the void swelling resistance of reduced-activation ferritic-martensitic steels CNS I and CNS II at high doses, ion irradiation was performed up to 188 dpa (4.6 × 1017 ion/cm2) at 460 °C using 5 MeV Fe++ ions. Helium was pre-implanted at levels of 10 and 100 appm at room temperature to investigate the role of helium on void swelling. Commercial FM steel T91 was also irradiated in this condition and the swelling results are of included in this paper as a reference. Voids were observed in all conditions. The 9Cr CNS I samples implanted with 10 appm helium exhibited lower swelling than 9Cr T91 irradiated at the same condition. The 12Cr CNS II with 10 and 100 appm helium showed significantly lower swelling than CNS I and T91. The swelling rate for CNS I and CNS II were determined to be 0.02%/dpa and 0.003%/dpa respectively. Increasing the helium content from 10 to 100 appm shortened the incubation region and increased the void density but had no effect on the swelling rates.
Molecular dynamics simulation analysis of ion irradiation effects on plasma-liquid interface
NASA Astrophysics Data System (ADS)
Minagawa, Yudai; Shirai, Naoki; Uchida, Satoshi; Tochikubo, Fumiyoshi
Nonthermal atmospheric plasmas are used in a wide range of fields because the high-density plasma can be easily irradiated to various substances such as solid, liquid, biological object and so on. On the other hand, the mechanisms of physical and chemical phenomena at the plasma-liquid interface are not well understood yet. To investigate the effects of ion impact from plasma on water surface, we analyzed behavior of liquid water by classical molecular dynamics simulation. Simulation system consists of an irradiation particle in gas phase and 2000 water molecules in liquid phase. O+ ion with 10 eV or 100 eV was impinged on the water surface. Ion impact induced increasing water temperature and ejection of water molecules. The averaged number of evaporated water molecules by ion impact is 0.6 molecules at 10 eV and 7.0 molecules at 100 eV. The maximum ion penetration depth was 1.14 nm at 10 eV and 2.75 nm at 100 eV. Ion entering into water disturbs the stable hydrogen bonding configurations between water molecules and gives energy to water molecules. Some water molecules rotated and moved by ion interaction impact on other water molecules one after another. When the water molecule near the surface received strongly repulsive force, it released into gas phase. Nonthermal atmospheric plasmas are used in a wide range of fields because the high-density plasma can be easily irradiated to various substances such as solid, liquid, biological object and so on. On the other hand, the mechanisms of physical and chemical phenomena at the plasma-liquid interface are not well understood yet. To investigate the effects of ion impact from plasma on water surface, we analyzed behavior of liquid water by classical molecular dynamics simulation. Simulation system consists of an irradiation particle in gas phase and 2000 water molecules in liquid phase. O+ ion with 10 eV or 100 eV was impinged on the water surface. Ion impact induced increasing water temperature and ejection of water molecules. The averaged number of evaporated water molecules by ion impact is 0.6 molecules at 10 eV and 7.0 molecules at 100 eV. The maximum ion penetration depth was 1.14 nm at 10 eV and 2.75 nm at 100 eV. Ion entering into water disturbs the stable hydrogen bonding configurations between water molecules and gives energy to water molecules. Some water molecules rotated and moved by ion interaction impact on other water molecules one after another. When the water molecule near the surface received strongly repulsive force, it released into gas phase. This work was supported financially in part by a Grant-in-Aid for Scientific Research on Innovation Areas (No21110007) from MEXT, Japan.
Annealing Effects on Transition Temperature of Superconductiong Bi-Sr-Ca-Cu-O Films after Ion Irradiation
Taiji Hoshiya; Saburo Takamura; Takeo Aruga; Mamoru Kobiyama
The effect of annealing after irradiation on the transition temperature is studied for polycrystalline Bi-Sr-Ca-Cu-O films irradiated by He ions at room temperature. The temperatures of the out-diffusion and the in-diffusion of oxygen are obtained by annealing in air and a vacuum. There is a large recovery stage around 200˜ 500°C on annealing in air after irradiation. The 110 K
I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar cells
Meulenberg, A; Ramani,; Radhakrishna, M C; Saif, A K
Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV lithium ions. Dark-IV analysis (with and without illumination) reveals differences in the effects of such irradiation on the different cell types
Densification, anisotropic deformation, and plastic flow of SiO2 during MeV heavy ion irradiation
Polman, Albert
Densification, anisotropic deformation, and plastic flow of SiO2 during MeV heavy ion irradiation E years,1 because of the potential use of silica in nuclear reactors and waste containers, and its current results in a tensile stress in the irradiated region. Stress can be relieved by radiation enhanced plastic
Optical alteration of complex organics induced by ion irradiation:. 1. Laboratory experiments suggest unusual space weathering trend
NASA Astrophysics Data System (ADS)
Moroz, Lyuba; Baratta, Giuseppe; Strazzulla, Giovanni; Starukhina, Larissa; Dotto, Elisabetta; Barucci, Maria Antonietta; Arnold, Gabriele; Distefano, Elisa
Most ion irradiation experiments relevant to primitive outer Solar System objects have been performed on ice and silicate targets. Here we present the first ion irradiation experiments performed on natural complex hydrocarbons (asphaltite and kerite). These materials are very dark in the visible and have red-sloped spectra in the visible and near-infrared. They may be comparable in composition and structure to refractory organic solids on the surfaces of primitive outer Solar System objects. We irradiated the samples with 15-400 keV H +, N +, Ar ++, and He + ions and measured their reflectance spectra in the range of 0.3-2.5 ?m before ion implantation and after each irradiation step. The results show that irradiation-induced carbonization gradually neutralizes the spectral slopes of these red organic solids. This implies a similar space weathering trend for the surfaces of airless bodies optically dominated by spectrally red organic components. The reduction of spectral slope was observed in all experiments. Irradiation with 30 keV protons, which transfers energy to the target mostly via electronic (inelastic) collisions, showed lower efficiency than the heavier ions. We found that spectral alteration in our experiments increased with increasing contribution of nuclear versus electronic energy loss. This implies that nuclear (elastic) energy deposition plays an important role in changing the optical properties of irradiated refractory complex hydrocarbon materials. Finally, our results indicated that temperature variations from 40 K to room temperature did not influence the spectral properties of these complex hydrocarbon solids.
Effect of ion beam irradiation on magnetism of Fe(100) outermost surfaces studied by spin-polarized ion scattering spectroscopy
NASA Astrophysics Data System (ADS)
Suzuki, T. T.; Kuwahara, H.; Yamauch, Y.
We study the effect of 2 keV Ar+ ion beam irradiation (IBI) on the outermost surface magnetism of an Fe(100) film by spin-polarized ion scattering spectroscopy (SP-ISS). We found that the coercivity of the outermost surface is enhanced with IBI. On the other hand, spin polarization is independent of IBI. These effects of IBI on surface magnetism are discussed in terms of morphology and atomic arrangement of the surface analyzed by ISS and reflection high-energy electron diffraction. The variation of coercivity with respect to the average iron film thickness d followed a power law d- n with the assumption that d is linearly dependent on the IBI time.
Non-equilibrium structures induced by ion irradiation in Ni{sub 4}Mo
Bellon, P. [CEREM/SRMP, CE Saclay, Gif-sur-Yvette (France); Okamoto, P.R. [Argonne National Lab., IL (United States); Schumacher, G. [Hahn-Meitner-Institut Berlin GmbH (Germany)
We have studied the stability of equilibrium and metastable ordered phases (called LRO and SRO respectively) in Ni{sub 4}Mo during 500-keV Ne or 250-keV He irradiations. Some irradiations were performed in situ, allowing thus to follow the evolution of the samples, which were characterized by Transmission Electron Microscopy. Dynamical equilibrium phase diagrams are built, by varying the irradiation flux, temperature and dose. At a fixed ion flux, there exists a temperature range were a ``mixed`` ordered state is stabilized, and remains stable up to the maximum doses reached (1.7 dpa). This state, which cannot be obtained by electron irradiation, consists in the coexistence of the two ordered phases at a very fine scale ({le} 2nm). Comparison with results already reported after electron irradiation is made, stressing the role played by displacement cascades in our results. Furthermore we observed alignment of dislocation loops along, the [001] c-axis of the quadratic LRO phase.
Non-equilibrium structures induced by ion irradiation in Ni[sub 4]Mo
Bellon, P. (CEREM/SRMP, CE Saclay, Gif-sur-Yvette (France)); Okamoto, P.R. (Argonne National Lab., IL (United States)); Schumacher, G. (Hahn-Meitner-Institut Berlin GmbH (Germany))
We have studied the stability of equilibrium and metastable ordered phases (called LRO and SRO respectively) in Ni[sub 4]Mo during 500-keV Ne or 250-keV He irradiations. Some irradiations were performed in situ, allowing thus to follow the evolution of the samples, which were characterized by Transmission Electron Microscopy. Dynamical equilibrium phase diagrams are built, by varying the irradiation flux, temperature and dose. At a fixed ion flux, there exists a temperature range were a mixed'' ordered state is stabilized, and remains stable up to the maximum doses reached (1.7 dpa). This state, which cannot be obtained by electron irradiation, consists in the coexistence of the two ordered phases at a very fine scale ([le] 2nm). Comparison with results already reported after electron irradiation is made, stressing the role played by displacement cascades in our results. Furthermore we observed alignment of dislocation loops along, the [001] c-axis of the quadratic LRO phase.
Pair breaking by chain oxygen disorder in ion irradiated YBCO thin films
NASA Astrophysics Data System (ADS)
Arias, Diego; Sefrioui, Zouhair; Varela, Maria; Leon, Carlos; Santamaria, Jacobo; Agullo-Rueda, Fernando
In this communication we report on the irradiation of oxygen depleted YBa 2 Cu_3O7 thin films with light ions (He+) at energies in the range 40-160 keV, and at doses comprised between 10^12cm-2and 10^15cm-2. Raman scattering has been used to show that the oxygen content and the integrity of the CuO planes is essentially preserved. A comparison between samples with thermal disorder and irradiated samples shows that defect centers created by irradiation are related to oxygen displacements in the chains, and produce significant scattering, although the carrier concentration is not modified substantially. A reduction of the critical temperature and an increase of the resistivity are observed upon irradiation, which is discussed in terms of pair breaking caused by the irradiation induced scattering centers in the CuO chains. 1 On leave from Universidad del Quindio. Armenia Colombia Acknowledgements: Work supported by CICYT MAT2000 1468.
The influence of 175 MeV Ni13+ ion and Co-60 gamma irradiation effects on subthreshold characteristics of N-channel depletion MOSFETs
NASA Astrophysics Data System (ADS)
Pushpa, N.; Praveen, K. C.; Prakash, A. P. Gnana; Naik, P. S.; Gupta, S. K.; Revannasiddaiah, D.
N-channel depletion metal oxide semiconductor field effect transistors (MOSFETs) were irradiated with 175 MeV Ni3+ ions and Co-60 gamma radiation in the dose range of 100 krad to 100 Mrad. The I-V characteristics of MOSFETs were studied systematically before and after ion and gamma irradiation. The threshold voltage (VTH) of the irradiated MOSFETs was found to decrease with increase in ion and gamma dose. The more degradation was observed in the devices irradiated with Co-60 gamma radiation than irradiated with Ni13+ ions at given total doses.
Ion Tracks and Microstructures in Barium Titanate Irradiated with Swift Heavy Ions: A Combined Experimental and Computational Study
Jiang, Weilin; Devanathan, Ramaswami; Sundgren, Christina J.; Ishimaru, Manabu; Sato, Kazuhisa; Varga, Tamas; Manandhar, Sandeep; Benyagoub, Abdenacer
Tetragonally structured BaTiO3 single crystals were irradiated using 635 MeV 238U+ ions to fluences of 1E7, 5E10 and 1.4E12 ions/cm2 at room temperature. Subsequent sample characterizations were performed using ion channeling, x-ray diffraction (XRD), helium ion microscopy, and transmission electron microscopy. The results show that there are lattice relaxation and recovery of pre-existing defects in the irradiated samples. Various structures representing different regimes of electronic and nuclear interactions along the ion track are observed. The track on the surface has an amorphous core of up to ~10 nm in diameter, surrounded by a strained lattice structure. The core size is roughly proportional to the square root of the electronic stopping power. Satellite-like defects around the core are also present. The ring of cubic phase expected to form around the amorphous core does not appear, probably due to a reversible phase transition as confirmed by an in-situ XRD study. Modeling and simulation are also attempted to interpret the data and gain physical insights. We have developed a partial charge model for cubic BaTiO3 that reproduces its lattice constants, elastic constants, and melting temperature. Using the interatomic potential, we have performed molecular dynamics simulations of the irradiation damage in BaTiO3. The results show that an amorphous track of ~1.2 nm in radius forms under thermal energy deposition at dE(T)/dx = 5 keV/nm. At 20 keV/nm, the radius increases to ~4.5 nm with an order of magnitude increase in the number of defects. The simulation also reveals details of the bonding environments and shows that the amorphous zones produced at different dE(T)/dx values have different densities. The combined experimental and computational data suggest that there is a significant interfacial recrystallization of the as-created amorphous cores during the cooling-down stage of thermal spikes.
Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2 Si interfaces
Perez-Bergquist, Alex G [ORNL] [ORNL; Zhang, Yanwen [ORNL] [ORNL; Varga, Tamas [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Moll, Sandra [TN International / AREVA, 1, rue des Hérons, 78182 Montigny Le Bretonneux, France] [TN International / AREVA, 1, rue des Hérons, 78182 Montigny Le Bretonneux, France; Namavar, Fereydoon [University of Nebraska Medical Center] [University of Nebraska Medical Center; Weber, William J [ORNL] [ORNL
Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to 4 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0 1.5 MeV), and at varying temperatures (160 600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.
Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2-Si interfaces
NASA Astrophysics Data System (ADS)
Perez-Bergquist, Alejandro G.; Zhang, Yanwen; Varga, Tamas; Moll, Sandra; Namavar, Fereydoon; Weber, William J.
Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to ˜4 × 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0-1.5 MeV), and at varying temperatures (160-600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.
Modification of microstructure and hardness for Cu-Ti alloy by means of energetic ion beam irradiation
NASA Astrophysics Data System (ADS)
Ueyama, D.; Semboshi, S.; Saitoh, Y.; Hori, F.; Nishida, K.; Soneda, N.; Iwase, A.
Cu-Ti alloys were irradiated with 5.4 MeV Al ions, 7.3 MeV Fe ions, 10 MeV I ions, and 16 MeV Au ions at room temperature and the Vickers microhardness was measured. The hardness once increases by the irradiation with a low fluence, and then it remains almost constant even with increasing the ion fluence. The change in hardness was well correlated with the density of energy deposited through the elastic collisions and not the electronic excitation. The observation of atom probe tomography (APT) did not show any Ti clusters in the irradiated specimens. This result suggests that not Ti clusters but lattic defects (interstitial atoms, vacancies and/or their aggregates) contributed to the increase in hardness of Cu-Ti alloys.
Development of a facility for high-precision irradiation of cells with carbon ions
Goethem, Marc-Jan van; Niemantsverdriet, Maarten; Brandenburg, Sytze; Langendijk, Johannes A.; Coppes, Robert P.; Luijk, Peter van [Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713AV Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands); Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747AA Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands); Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713AV Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands)
Purpose: Compared to photons, using particle radiation in radiotherapy reduces the dose and irradiated volume of normal tissues, potentially reducing side effects. The biological effect of dose deposited by particles such as carbon ions, however, differs from that of dose deposited by photons. The inaccuracy in models to estimate the biological effects of particle radiation remains the most important source of uncertainties in particle therapy. Improving this requires high-precision studies on biological effects of particle radiation. Therefore, the authors aimed to develop a facility for reproducible and high-precision carbon-ion irradiation of cells in culture. The combined dose nonuniformity in the lateral and longitudinal direction should not exceed {+-}1.5%. Dose to the cells from particles than other carbon ions should not exceed 5%. Methods: A uniform lateral dose distribution was realized using a single scatter foil and quadrupole magnets. A modulator wheel was used to create a uniform longitudinal dose distribution. The choice of beam energy and the optimal design of these components was determined using GEANT4 and SRIM Monte Carlo simulations. Verification of the uniformity of the dose distribution was performed using a scintillating screen (lateral) and a water phantom (longitudinal). The reproducibility of dose delivery between experiments was assessed by repeated measurements of the spatial dose distribution. Moreover, the reproducibility of dose-response measurements was tested by measuring the survival of irradiated HEK293 cells in three independent experiments. Results: The relative contribution of dose from nuclear reaction fragments to the sample was found to be <5% when using 90 MeV/u carbon ions. This energy still allows accurate dosimetry conforming to the IAEA Report TRS-398, facilitating comparison to dose-effect data obtained with other radiation qualities. A 1.3 mm long spread-out Bragg peak with a diameter of 30 mm was created, allowing the irradiation of cell samples with the specified accuracy. Measurements of the transverse and longitudinal dose distribution showed that the dose variation over the sample volume was {+-}0.8% and {+-}0.7% in the lateral and longitudinal directions, respectively. The track-averaged LET of 132{+-}10 keV/{mu}m and dose-averaged LET of 189{+-}15 keV/{mu}m at the position of the sample were obtained from a GEANT4 simulation, which was validated experimentally. Three separately measured cell-survival curves yielded nearly identical results. Conclusions: With the new facility, high-precision carbon-ion irradiations of biological samples can be performed with highly reproducible results.
Phase separation in ion-irradiated compound semiconductors: an alternate route to ordered nano-structures
Scott A. Norris
In recent years, observations of highly-ordered, hexagonal arrays of self-organized nanostructures on binary or impurity-laced targets under normal-incidence ion irradiation have excited interest in this phenomenon as a potential route to high-throughput, low-cost manufacture of nanoscale devices or nanostructured coatings. The currently-prominent explanation for these structures is a morphological instability driven by ion erosion discovered by Bradley and Shipman; however, recent parameter estimates via molecular dynamics simulations suggest that this erosive instability may not be active for the representative GaSb system in which hexagonal structures were first observed. Motivated by experimental and numerical evidence suggesting the possible importance of phase separation in ion-irradiated compounds, we here generalize the Bradley-Shipman theory to include the effect of ion-assisted phase separation. The resulting system admits a chemically-driven finite-wavelength instability that can explain the order of observed patterns even when the erosive Bradley-Shipman instability, and in a relevant simplifying limit, provides an intuitive instability criteria that agrees qualitatively with experimental observations on pattern wavelengths. Finally, we identify a characteristic experimental signature that distinguishes the chemical and morphological instabilities, and highlights the need for specific additional experimental data on the GaSb system.
Formation of cobalt silicides as a buried layer in silicon using high energy heavy ion irradiation
NASA Astrophysics Data System (ADS)
Chakraborty, B. R.; Halder, S. K.; Karar, N.; Kabiraj, D.; Avasthi, D. K.
A multilayer heterostructure of Si(50 nm)/Co(50 nm)/Si(50 nm)/Silang 100rang was prepared by an e-beam evaporation technique under UHV conditions and it was then subjected to irradiation by 120 MeV Au+ ions with fluence varying between 1013 and 1014 ions cm-2. No external thermal treatments were used. Secondary ion mass spectrometry was used in the depth profile mode, which indicated a monotonic increase in the mixing width with fluence at the first interface of Si/Co. Depth profile analysis suggested major changes in the preferential sputtering rates of Co at the interface indicating formation of silicides. Further investigation by x-ray diffraction confirmed the formation of different phases of cobalt silicides, Co2Si, CoSi and CoSi2, as a buried layer, while the Raman spectroscopy showed broad peaks near 325 and 725 cm-1, which are characteristic of the CoSi2 phase. The above work suggests that swift heavy ion irradiation can be advantageously used for interconnect related buried layer silicide formation at room temperature avoiding thermal annealing.
Dependence of cross sections for multi-electron loss by 6 mev/amu xe18+ ions on target atomic number
Peng, Yong
It has been proposed to use heavy ion beams with energies around 10 MeV/amu, masses around 200, and average charges of 1+ as a driver for inertial fusion reactor. Current designs require the beams to travel through a region where the background gas...
Carbon-Ion Beam Irradiation Kills X-Ray-Resistant p53-Null Cancer Cells by Inducing Mitotic Catastrophe
Amornwichet, Napapat; Oike, Takahiro; Shibata, Atsushi; Ogiwara, Hideaki; Tsuchiya, Naoto; Yamauchi, Motohiro; Saitoh, Yuka; Sekine, Ryota; Isono, Mayu; Yoshida, Yukari; Ohno, Tatsuya; Kohno, Takashi; Nakano, Takashi
Background and Purpose To understand the mechanisms involved in the strong killing effect of carbon-ion beam irradiation on cancer cells with TP53 tumor suppressor gene deficiencies. Materials and Methods DNA damage responses after carbon-ion beam or X-ray irradiation in isogenic HCT116 colorectal cancer cell lines with and without TP53 (p53+/+ and p53-/-, respectively) were analyzed as follows: cell survival by clonogenic assay, cell death modes by morphologic observation of DAPI-stained nuclei, DNA double-strand breaks (DSBs) by immunostaining of phosphorylated H2AX (?H2AX), and cell cycle by flow cytometry and immunostaining of Ser10-phosphorylated histone H3. Results The p53-/- cells were more resistant than the p53+/+ cells to X-ray irradiation, while the sensitivities of the p53+/+ and p53-/- cells to carbon-ion beam irradiation were comparable. X-ray and carbon-ion beam irradiations predominantly induced apoptosis of the p53+/+ cells but not the p53-/- cells. In the p53-/- cells, carbon-ion beam irradiation, but not X-ray irradiation, markedly induced mitotic catastrophe that was associated with premature mitotic entry with harboring long-retained DSBs at 24 h post-irradiation. Conclusions Efficient induction of mitotic catastrophe in apoptosis-resistant p53-deficient cells implies a strong cancer cell-killing effect of carbon-ion beam irradiation that is independent of the p53 status, suggesting its biological advantage over X-ray treatment. PMID:25531293
Effect of swift heavy ion irradiation on structure, optical, and gas sensing properties of SnO 2 thin films
NASA Astrophysics Data System (ADS)
Rani, Sanju; Puri, N. K.; Roy, Somnath C.; Bhatnagar, M. C.; Kanjilal, D.
Swift heavy ion irradiation has been successfully used to modify the structural, optical, and gas sensing properties of SnO 2 thin films. The SnO 2 thin films prepared by sol-gel process were irradiated with 75 MeV Ni + beam at fluences ranging from 1 × 10 11 ion/cm 2 to 3 × 10 13 ion/cm 2. Structural characterization with glancing angle X-ray diffraction shows an enhancement of crystallinity and systematic change of stress in the SnO 2 lattice up to a threshold value of 1 × 10 13 ions/cm 2, but decrease in crystallinity at highest fluence of 3 × 10 13 ions/cm 2. Microstructure investigation of the irradiated films by transmission electron microscopy supports the XRD observations. Optical properties studied by absorption and PL spectroscopies reveal a red shift of the band gap from 3.75 eV to 3.1 eV, and a broad yellow luminescence, respectively, with increase in ion fluence. Gas response of the irradiated SnO 2 films shows increase of resistance on exposure to ammonia (NH 3), indicating p-type conductivity resulting from ion irradiation.
Dielectric response of polyethersulphone (PES) polymer irradiated with 145 MeV Ne{sup 6+} ions
Ali, S. Asad; Khan, Wasi; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh-202002 (India); Kumar, Rajesh [University School of Basic and Applied Sciences, G.G.S.I.P. University, Delhi-110403 (India); Prasad, R. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh-202002 (India) and Vivekananda College of Technology and Management Aligarh-202002 (India)
Heavy ion irradiation produces modifications in polymers and adapts their electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission and formation of carbon rich clusters. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Polyethersulphone (PES) polymer film is carried out. 250 {mu}m thick PES films were irradiated to the fluences of 10{sup 12} and 10{sup 13} ions/cm{sup 2} with Ne{sup 6+} ions of 145 MeV energy from Variable Energy Cyclotron Centre, Kolkata On irradiation with heavy ions dielectric constant ({epsilon} Prime ) decreases at higher frequencies and increases with fluences. Variation of loss factor (tan {delta}) with frequency for pristine and irradiated with Si ions reveals that tan {delta} increases as the frequency increases. The tan{delta} also increases with fluence. Tan {delta} has positive values indicating the dominance of inductive behavior.
Time constant of defect relaxation in ion-irradiated 3C-SiC
NASA Astrophysics Data System (ADS)
Wallace, J. B.; Bayu Aji, L. B.; Shao, L.; Kucheyev, S. O.
Above room temperature, the buildup of radiation damage in SiC is a dynamic process governed by the mobility and interaction of ballistically generated point defects. Here, we study the dynamics of radiation defects in 3C-SiC bombarded at 100 °C with 500 keV Ar ions, with the total ion dose split into a train of equal pulses. Damage-depth profiles are measured by ion channeling for a series of samples irradiated under identical conditions except for different durations of the passive part of the beam cycle. Results reveal an effective defect relaxation time constant of ˜ 3 ms (for second order kinetics) and a dynamic annealing efficiency of ˜ 40 % for defects in both Si and C sublattices. This demonstrates a crucial role of dynamic annealing at elevated temperatures and provides evidence of the strong coupling of defect accumulation processes in the two sublattices of 3C-SiC.
Nanostructuring of InP surface by low-energy ion beam irradiation.
Mohanta, S K; Soni, R K; Tripathy, S; Chua, S J; Kanjilal, D
The InP nanodots of size 55 to 100 nm and height 25 to 30 nm have been synthesized by low-energy Ar+-ion irradiation with different ion energies. Sizes and size distributions of the dots strongly depend on growth conditions. Rapid thermal annealed (RTA) of the patterned surface shows cluster formation for annealing temperature 400 degrees C and above. Raman investigations reveal optical phonon softening due to correlation length shortening and broadening of the optical modes from the patterned surface. The softening is due to confinement of phonons in embedded nanocrystallites within the patterned surface along with surface nanodots, and broadening is attributed to their size distributions, which increases with increase in ion energy. The lattice damage recovery is observed from the patterned surface subjected to RTA, which exhibits upward shift of the LO and TO phonons due to the presence of complex interfacial stress, associated with the removal of crystal defects with RTA. PMID:17654989
Zenithal alignment of liquid crystal on homeotropic polyimide film irradiated by ion beam
We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality. PMID:22221956
Density of hydroxyl radicals generated in an aqueous solution by irradiating carbon-ion beam.
Matsumoto, Ken-ichiro; Ueno, Megumi; Nakanishi, Ikuo; Anzai, Kazunori
The density of hydroxyl radicals (·OH) produced in aqueous samples by exposure to X-ray or carbon-ion beams was investigated. The generation of ·OH was detected by the electron paramagnetic resonance (EPR) spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. When the concentration of DMPO is in excess of the generated ·OH, the production of DMPO-OH (spin-trapped ·OH) should be saturated. Reaction mixtures containing several concentrations (0.5-1685?mM) of DMPO were then irradiated by a 32?Gy 290?MeV carbon-ion beam (C290-beam) or X-ray. C290-beam irradiation was performed at the Heavy-Ion Medical Accelerator in Chiba (HIMAC, National Institute of Radiological Sciences, Chiba, Japan), applying different linear energy transfers (LET) (20-169?keV/µm). The amount of DMPO-OH in the irradiated samples was detected by EPR spectroscopy. The generation of DMPO-OH increased with the concentration of initial DMPO, displayed a shoulder around 3.3?mM DMPO, and reached a plateau. This plateau suggests that the generated ·OH were completely trapped. Another linear increase in DMPO-OH measured in solutions with higher DMPO concentrations suggested very dense ·OH generation (>1.7?M). Generation of ·OH is expected to be localized on the track of the radiation beam, because the maximum concentration of measured DMPO-OH was 40?µM. These results suggested that both sparse (?3.3?mM) and dense (>1.7?M) ·OH generation occurred in the irradiated samples. The percentage of dense ·OH generation increased with increasing LET. Different types of dense ·OH generation may be expected for X-ray and C290-beams. PMID:25757490
Mass and double-beta-decay Q value of 136Xe.
Redshaw, Matthew; Wingfield, Elizabeth; McDaniel, Joseph; Myers, Edmund G
The atomic mass of 136Xe has been measured by comparing cyclotron frequencies of single ions in a Penning trap. The result, with 1 standard deviation uncertainty, is M(136Xe)=135.907 214 484 (11) u. Combined with previous results for the mass of 136Ba [Audi, Wapstra, and Thibault, Nucl. Phys. A 729, 337 (2003)10.1016/j.nuclphysa.2003.11.003], this gives a Q value (M[136Xe]-M[136Ba])c(2)=2457.83(37) keV, sufficiently precise for ongoing searches for the neutrinoless double-beta decay of 136Xe. PMID:17358854
Antiradiation vaccine: Technology and development of prophylaxis, prevention and treatment of biological consequences from Heavy Ion irradiation.
NASA Astrophysics Data System (ADS)
Popov, Dmitri; Maliev, Vecheslav
Introduction: An anti-radiation vaccine could be an important part of a countermeasures reg-imen for effective radioprotection, immunoprophylaxis and immunotherapy of the acute radi-ation syndromes (ARS) after gamma-irradiation, neutron irradiation or heavy ion irradiation. Reliable protection of non-neoplastic regions of patients with different forms of cancer which undergo to heavy ion therapy ( e.g. Hadron-therapy) can significantly extend the efficiency of the therapeutic course. The protection of cosmonauts astronauts from the heavy ion ra-diation component of space radiation with specific immunoprophylaxis by the anti-radiation vaccine may be an important part of medical management for long term space missions. Meth-ods and experiments: 1. The Antiradiation Vaccine preparation -standard (mixture of toxoid form of Radiation Toxins -SRD-group) which include Cerebrovascular RT Neurotoxin, Car-diovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins Specific Radiation Determinant Group were isolated from a central lymph of gamma-irradiated animals with Cerebrovascular, Cardiovascular, Gastrointestiinal, Hematopoi-etic forms of ARS. Devices for ?-radiation are "Panorama", "Puma". 2. Heavy ion exposure was accomplished at Department of Scientific Research Institute of Nuclear Physics, Dubna, Russia. The heavy ions irradiation was generated in heavy ion (Fe56) accelerator -UTI. Heavy Ion linear transfer energy -2000-2600 KeV mkm, 600 MeV U. Absorbed Dose -3820 Rad. 3. Experimental Design: Rabbits from all groups were irradiated by heavy ion accelerator. Group A -control -10 rabbits; Group B -placebo -5 rabbits; Group C -radioprotectant Cystamine (50 mg kg)-5 rabbits, 15 minutes before irradiation -5 rabbits; Group D -radioprotectant Gammafos (Amifostine -400mg kg ), -5 rabbits; Group E -Antiradiation Vaccine: subcuta-neus administration or IM -2 ml of active substance, 14 days before irradiation -5 rabbits. 4. Results: Group A -100% mortality within two hours after heavy ion irradiation with clinical symptoms of the acute cerebrovascular and cardiovascular syndromes. Group B -100% mortal-ity within 15 hours following irradiation. Group C -100% mortality within 14-15 hours after irradiation. Group D -100% mortality within 15-16 hours after irradiation. In groups A-D, development of the acute radiation cerebrovascular and cardiovascular syndromes as well as ex-tensive burns of skin caused rapid death. Group E -100% mortality in 280-290 hours (12 days) following heavy ion irradiation while animals were exhibiting a combination or individual forms of the acute cerebrovascular, cardiovascular, and gastrointestinal forms and focal skin burns. Discussion: The Antiradiation Vaccine (ARV) and specific immune-prophylaxis are an effective method of neutralization of Radiation Toxins. Vaccination with the ARV significantly extended the survival time after irradiation with heavy ions from two hours up to 300 hours. Clinical signs, clinical features, symptoms were somewhat attenuated. Degree of clinical forms of the Acute Radiation Syndromes were diminished in their severity. Groups A-D demonstrated an extremely severe degree (Degree 4) of Cerebrovascular and Cardiovascular forms of the Acute Radiation Syndromes and lethality 100% was registered in a short time after irradiation. Radi-ation induced burns in this groups (with Cutaneous sub-syndrome of ARS -Degree 4) that were deep with extensive and total dysfunction and possible muscle involvement developed. Animals from group E -Radioprotectant -anti-radiation vaccine had demonstrated later development of the severe Degree 3 or even Degree 2-3 forms of Cerebrovascular and Cardiovascular forms of the ARS and a survival time of irradiated animals was significantly prolonged. Cutaneous sub-syndrome developed in Degree 3 or Degree 2-3. Our results have demonstrated the potential radioprotection efficacy of specific immune-prophylaxis with the Antiradiation vaccine against heavy ion irradiation.
Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method
Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)
Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.
Effect of Swift Heavy ion Irradiation on Ce Doped CaS Nanophosphors
NASA Astrophysics Data System (ADS)
Sharma, Geeta; Gosavi, S. W.; Lochab, S. P.; Singh, Nafa
Research in the field of Material Science has gained an upthrust because of the use of high energy charged particles such as swift heavy ions. Swift heavy ions (SHI) lose energy in materials mainly through inelastic collisions with the atomic electrons leading to the modifications in the properties of the material. Now a day it has become a probe to investigate and enhance various properties of the materials. In the present study CaS: Ce nanophosphors, synthesized via solid state diffusion method were irradiated with 120 MeV Ni+9 ions at three different fluences of 1×1011, 1×1012, and 5×1012 ion/cm2. The phosphors were structurally and optically characterized using X-Ray Diffraction and Photoluminescence spectroscopy respectively. The average particle size decreased with increasing ion fluence. It is found that the PL emission peak observed at 505 nm has increased in intensity with increasing ion fluence which can make it a better candidate for practical applications such as in optical devices.
Fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates using XeF 2 enhanced focused ion-beam etching
J. Kettle; R. T. Hoyle; S. Dimov
The fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates with line widths of 50 nm is described in this work.\\u000a The structures have been patterned using a Ga+ focused ion beam (FIB) in a quartz template. FIB milling is generally accompanied with re-deposition effects, which represent\\u000a a hindrance to densely patterned nanostructures required in most NIL applications. To reduce these re-deposition effects,
Explosion of atomic clusters irradiated by high-intensity laser pulses: Scaling of ion energies with cluster and laser parameters
Ditmire, Todd
, with a view to experimental optimization of the cluster explosion temperature. The noble-gas clusters were as noble-gas clusters explode. The ions are stripped to very high charge states 1,3,4 and the x-ray yieldExplosion of atomic clusters irradiated by high-intensity laser pulses: Scaling of ion energies
Molecular vibration spectroscopy study of irradiation effect in C{sub 60} films induced by low energy ion
Fu Yunchong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduated School of Chinese Academy of Sciences, Beijing 100049 (China); Jin Yunfan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)
Irradiation effect in C{sub 60} films induced by 170 keV B ion was investigated by means of Fourier transform infrared (FTIR) and Raman spectroscopies. The damage cross section {sigma} and the effective damage radius R are deduced from the experimental data of all four IR active modes and evident four Raman active modes of C{sub 60} molecule. The differences on irradiation sensitivity and structural stability of the different active modes of C{sub 60} molecule are compared. The results indicate that T{sub 1u} (4) of infrared active mode and A{sub g} (1) of Raman active mode are most sensitive for B ion irradiation. On the other hand T{sub 1u} (2) of infrared active mode and H{sub g} (3) of Raman active mode are comparatively stable under B ion irradiation.
Nano-welding and junction formation in hydrogen titanate nanowires by low-energy nitrogen ion irradiation
NASA Astrophysics Data System (ADS)
Dhal, Satyanarayan; Chatterjee, Shyamal; Sarkar, Subhrangsu; Tribedi, Lokesh C.; Bapat, Rudheer; Ayyub, Pushan
Crystalline hydrogen titanate (H2Ti3O7) nanowires were irradiated with N+ ions of different energies and fluences. Scanning electron microscopy reveals that at relatively lower fluence the nanowires are bent and start to adhere strongly to one another as well as to the silicon substrate. At higher fluence, the nanowires show large-scale welding and form a network of mainly 'X' and 'Y' junctions. Transmission electron microscopy and Raman scattering studies confirm a high degree of amorphization of the nanowire surface after irradiation. We suggest that while ion-irradiation induced defect formation and dangling bonds may lead to chemical bonding between nanowires, the large scale nano-welding and junction network formation can be ascribed to localized surface melting due to heat spike. Our results demonstrate that low energy ion irradiation with suitable choice of fluence may provide an attractive route to the formation and manipulation of large-area nanowire-based devices.
Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix
NASA Technical Reports Server (NTRS)
Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.
Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We also obtained O Ka spectra from phyllosilicates in both regions of the sample. The O Ka spectra show a pre-edge feature at approximately 530.5 electronvolts that is related to O 2p states hybridized with Fe 3d states. The intensity ratio of the O Ka pre-edge peak relative to the main part of the O Ka edge (that results from transitions of O 1s to 2p states) is lower in the irradiated layer compared to the pristine material and may reflect the loss of O (as OH) as was observed by IR spectroscopy. Conclusions: In addition to amorphization and OH loss, EELS spectra of He(+) irradiated matrix phyllosilicates in Murchison show that some of the Fe(3+) is reduced to Fe(2+). Spectral deconvolution is underway to extract quantitative ratios from the EELS spectra.
Cavity morphology in a Ni based superalloy under heavy ion irradiation with hot pre-injected helium. II
NASA Astrophysics Data System (ADS)
Zhang, He; Yao, Zhongwen; Daymond, Mark R.; Kirk, Marquis A.
In the current investigation, TEM in-situ heavy ion (1 MeV Kr2+) irradiation with helium pre-injected at elevated temperature (400 °C) was conducted to simulate in-reactor neutron irradiation induced damage in CANDU spacer material Inconel X-750, in an effort to understand the effects of helium on irradiation induced cavity microstructures. Three different quantities of helium, 400 appm, 1000 appm, and 5000 appm, were pre-injected directly into TEM foils at 400 °C. The samples containing helium were then irradiated in-situ with 1 MeV Kr2+ at 400 °C to a final dose of 5.4 dpa (displacement per atom). Cavities were formed from the helium injection solely and the cavity density and size increased with increasing helium dosage. In contrast to previous heavy ion irradiations with cold pre-injected helium, heterogeneous nucleation of cavities was observed. During the ensuing heavy ion irradiation, dynamical observation showed noticeable size increase in cavities which nucleated close to the grain boundaries. A "bubble-void" transformation was observed after Kr2+ irradiation to high dose (5.4 dpa) in samples containing 1000 appm and 5000 appm helium. Cavity distribution was found to be consistent with in-reactor neutron irradiation induced cavity microstructures. This implies that the distribution of helium is greatly dependent on the injection temperature, and helium pre-injection at high temperature is preferred for simulating the migration of the transmutation produced helium.
Cavity morphology in a Ni based superalloy under heavy ion irradiation with hot pre-injected helium. II
Zhang, He; Yao, Zhongwen, E-mail: email@example.com; Daymond, Mark R. [Department of Mechanical and Materials Engineering, Queen's University Kingston, Ontario K7L 3N6 (Canada); Kirk, Marquis A. [Material Science Division, Argonne National Laboratory Argonne, Illinois 60439 (United States)
In the current investigation, TEM in-situ heavy ion (1?MeV Kr{sup 2+}) irradiation with helium pre-injected at elevated temperature (400?°C) was conducted to simulate in-reactor neutron irradiation induced damage in CANDU spacer material Inconel X-750, in an effort to understand the effects of helium on irradiation induced cavity microstructures. Three different quantities of helium, 400 appm, 1000 appm, and 5000 appm, were pre-injected directly into TEM foils at 400?°C. The samples containing helium were then irradiated in-situ with 1?MeV Kr{sup 2+} at 400?°C to a final dose of 5.4 dpa (displacement per atom). Cavities were formed from the helium injection solely and the cavity density and size increased with increasing helium dosage. In contrast to previous heavy ion irradiations with cold pre-injected helium, heterogeneous nucleation of cavities was observed. During the ensuing heavy ion irradiation, dynamical observation showed noticeable size increase in cavities which nucleated close to the grain boundaries. A "bubble-void" transformation was observed after Kr{sup 2+} irradiation to high dose (5.4?dpa) in samples containing 1000 appm and 5000 appm helium. Cavity distribution was found to be consistent with in-reactor neutron irradiation induced cavity microstructures. This implies that the distribution of helium is greatly dependent on the injection temperature, and helium pre-injection at high temperature is preferred for simulating the migration of the transmutation produced helium.
Amorphization of rare earth aluminate garnets under ion irradiation and decay of ²??Cm admixture
Livshits, T. S. [Russian Academy of Sciences (RAS), Moscow (Russian Federation).; Lizin, A. A. [Joint Stock Co., State Scientific Center – Research Inst. of Atomic Reactors (JSC SSC-RIAR), Dimitrovgrad (Russian Federation); Zhang, J. M. [Univ. of Michigan, Ann Arbor, MI (United States); Ewing, R. C. [Univ. of Michigan, Ann Arbor, MI (United States)
The stability of synthetic REE-aluminate garnets irradiated by accelerated Kr2+ ions and affected by alpha decay of ²??Cm (T1/2 = 18.1 yr) has been studied. The dose of irradiation sufficient for the complete disordering of the aluminate garnet structure is 0.40–0.55 displacements per atom. This value increases with rising temperature due to the increasing intensity of recovery from radiation damage to the lattice by heating. The critical temperature above which the structure of REE-aluminate is not damaged by radiation is 550°C. The amorphization dose for aluminates with garnet structure is two to three times higher than of that previously studied ferrites; the critical temperature of both is similar. In resistance to radiation, aluminate garnets do not yield to zirconolite and exceed titanate pyrochlore. Heating to 250°C does not lead to substantial recovery from radiation defects in the garnet structure. The radiation impact on matrices of real actinide (An) wastes is lower than that related to ion irradiation and ²??Cm doping, and this facilitates a higher radiation resistance of garnets containing HLW.
Radiation tolerant nanocrystalline ZrN films under high dose heavy-ion irradiations
NASA Astrophysics Data System (ADS)
Jiao, L.; Yu, K. Y.; Chen, D.; Jacob, C.; Shao, L.; Zhang, X.; Wang, H.
ZrN, a refractory ceramic material, finds many potential applications in advanced nuclear reactors. However, the grain size dependent radiation response in nanocrystalline (nc) ZrN under high dose heavy ion irradiation has not yet been studied to date. Here, we compare the radiation response of nc-ZrN films (with a respective average grain size of ˜9 and 31 nm) to Fe2+ ion irradiations up to a damage level of 10 displacements-per-atom (dpa). The ZrN film with the average grain size of 9 nm shows prominently enhanced radiation tolerance as evidenced by suppressed grain growth, alleviated radiation softening, as well as reduced variation in electrical resistivity. In contrast, ZrN with the larger average grain size of 31 nm shows prominent radiation softening and resistivity increase, attributed to the high density of defect cluster formed inside the grains. The influence of grain boundaries on enhanced irradiation tolerance in nc-ZrN is discussed.
Mutation effects of C2+ ion irradiation on the greasy Nitzschia sp.
Yang, Y N; Liu, C L; Wang, Y K; Xue, J M
Screening and nurturing algae with high productivity, high lipid content and strong stress resistance are very important in algae industry. In order to increase the lipid content, the Nitzschia sp. was irradiated with a 3MeV C(2+) beam. The sample pretreatment method was optimized to obtain the best mutagenic condition and the survival ratio curve. The positive mutants with a significant improvement in lipid content were screened and their C(2+) mutagenic effects were analyzed by comparing the greasiness and growth characteristics with the wild type algae. Results showed that when the Nitzschia sp. was cultivated in nutritious medium containing 10% glycerol solution, and dried on the filter for 5 min after centrifugation, the realization of the microalgae heavy ion mutagenesis could be done. The survival ratio curve caused by C(2+) irradiation was proved to be "saddle-shaped". A positive mutant was screened among 20 survivals after irradiation, the average lipid content of the mutation increased by 9.8% than the wild type after 4 generations. But the growth rate of the screened mutation didn't change after the heavy ion implantation compared to the wild type algae. PMID:24064032
Solute segregation and microstructural evolution in ion-irradiated vanadium-base alloys
Loomis, B.A.; Kestel, B.J.; Gerber, S.B.
The microstructural evolution in V+14.7 a/o Cr, V+2.5 a/o Mo, V+2.5 a/o W, V+8.0 a/o Ni, V+5.3 a/o Ti, V+14.7 a/o Cr + 5.2 a/o Ti, V+9.6 a/o Cr + 3.1 a/o Fe+0.7 a/o Zr, and V+3.2 a/o Ti + 1.8 a/o Si alloys, and unalloyed V was determined from observations of specimens by TEM following 4.0-MeV /sup 51/V/sup + +/ ion irradiation at 900 to 970/sup 0/K to 50 dpa. The RIS of solutes in the ion-irradiated alloys was investigated by AES, EDXS, and EELS analyses. The RIS of solutes and microstructural evolution in the irradiated alloys were correlated with the solute diffusivity and the relative chemical affinity of the substitutional solutes for oxygen.
X-ray diffraction study of damage induced by swift heavy ion irradiation in fluorapatite
NASA Astrophysics Data System (ADS)
Miro, S.; Grebille, D.; Chateigner, D.; Pelloquin, D.; Stoquert, J.-P.; Grob, J.-J.; Costantini, J.-M.; Studer, F.
X-ray powder and high-resolution single-crystal diffraction techniques were used to study the irradiation damage of fluorapatites. Krypton, iodine and carbon irradiations were performed at high energy (?1 MeV/a) in the 1011 to 5 × 1013 cm-2 fluence range. Both diffraction techniques showed a strong unit-cell increase of the fluorapatite structure, with a full relaxation of the remaining part of the material for large fluences. X-ray powder experiments revealed an amorphization of the material up to 85% for fluences around 1013 ions cm-2. Simulation of the relationship between amorphous volume fraction and fluence evidenced that the amorphization mechanisms could be dominated by a single impact process for iodine and double impacts for krypton. The effective radius of the track core remained nearly constant although the electronic energy loss increases from Kr to I. Moreover total amorphization of fluorapatite irradiated by swift heavy ions could not be obtained in this study. Experiments performed on (0 0 2)-oriented single-crystals allowed us to separate the change of the c-parameters of the damaged and virgin phases, and pointed out an anisotropic response of the material to the damage process.
Positron annihilation and TEM studies on ion irradiated Fe and Fe-Cr model alloys of ferritic/martensitic steel
NASA Astrophysics Data System (ADS)
Huang, S. S.; Sato, K.; Xu, Q.; Yoshiie, T.; Tsuchida, H.; Itoh, A.
Fe ion irradiation-induced defects in F82H model alloys were studied using positron annihilation lifetime measurements. Irradiation was performed with an accelerating voltage of 6.0 MeV to a dose of 22 dpa at 593 K. In addition, a comparative study was conducted with results from our previous neutron irradiation measurements for F82H model alloys. The results showed an apparent decrease of the mobility of interstitial clusters in Fe by addition of Cr. This finding supports the configuration model of Cr on void swelling resistance in Fe-Cr alloys. A remarkable delay of defect structural evolution was also observed by ion irradiation compared to neutron irradiation because of a high damage rate.
Observations of void swelling in selected austenitic alloys during ion irradiation under a rising temperature ramp
NASA Astrophysics Data System (ADS)
Mazey, D. J.; Williams, T. M.; Bolster, D. E. J.
Results are given of a TEM study of the void swelling behaviour of CW AISI 321 (En58B), CW FV548 stainless steel and STA Nimonic PE16 alloy during 46 MeV nickel ion irradiation under a near-linear rising temperature ramp. The dose range for the ramp was 0-75 dpa and four temperature ranges were investigated using 50 ° C intervals from 500-550 ° C, 525-575 ° C, 575-625 ° C and 625-675 ° C. Swelling in CW 321 was found to be no greater than that observed after isothermal irradiation to 75 dpa at temperatures corresponding to the end-of-ramp temperatures. This was not the case for CW FV548 where the swelling for the temperature ranges of 525-575 ° C and 575-625 ° C was slightly greater than that observed under isothermal irradiation to 75 dpa. Swelling in STA PE16 in the lower temperature ranges of 500-550 ° C and 525-575°C was much higher than corresponding isothermal values but in the 600-700 ° C temperature range the swelling was close to isothermal values. The results on PE16 indicate that a steady increase in irradiation temperature from just below or just above the low temperature cut-off into the void swelling region produces a significant increase in swelling with respect to that expected under isothermal conditions. Possible interpretations of the observed swelling behaviour in these alloys are discussed.
Imaging Thomson scattering measurements of radiatively heated Xe
Pollock, B; Meinecke, J; Kuschel, S; Ross, J S; Divol, L; Glenzer, S H; Tynan, G R
Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 {micro}m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 {micro}m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the spatial electron density and temperature profile, and using these parameters as constraints in the ion feature analysis allows an accurate determination of the charge state of the Xe ions. The Thomson scattering probe beam is 40 J, 200 ps, and 527 nm, and is focused to a 100 {micro}m spot size at the entrance of the Pb cavity. Each system has a spatial resolution of 25 {micro}m, a temporal resolution of 200 ps (as determined by the probe duration), and a spectral resolution of 2 nm for the electron feature system and 0.025 nm for the ion feature system. The experiment is performed in a Xe filled target chamber at a neutral pressure of 3-10 Torr, and the x-rays produced in the Pb ionize and heat the Xe to a charge state of 20 {+-} 4 at up to 200 eV electron temperatures.
Effect of high-intensity pulsed ion beams irradiation on corrosion resistance of 316L stainless steel
X. Wang; X. G. Han; M. K. Lei; J. S. Zhang
High-intensity pulsed ion beam (HIPIB) treatment is a new technology for surface modification of materials. In this paper, the surface of 316L stainless steel was irradiated by high-intensity pulsed ion beams at ion current density of 100, 200 and 300A\\/cm2 with 1, 5 and 10 shots. The surface morphology and the phase structure in the near surface region of original
Effect of ion beam irradiation on the structure of ZnO films deposited by a dc arc plasmatron.
Penkov, Oleksiy V; Lee, Heon-Ju; Plaksin, Vadim Yu; Ko, Min Gook; Joa, Sang Beom; Yim, Chan Joo
The deposition of polycrystalline ZnO film on a cold substrate was performed by using a plasmatron in rough vacuum condition. Low energy oxygen ion beam generated by a cold cathode ion source was introduced during the deposition process. The change of film property on the ion beam energy was checked. It is shown that irradiation by 200 eV ions improves crystalline structure of the film. Increasing of ion beam energy up to 400 eV leads to the degradation of a crystalline structure and decreases the deposition rate. PMID:18315247
Chromosome aberration yields and apoptosis in human lymphocytes irradiated with Fe-ions of differing LET
NASA Astrophysics Data System (ADS)
Lee, R.; Nasonova, E.; Ritter, S.
In the present paper the relationship between cell cycle delays induced by Fe-ions of differing LET and the aberration yield observable in human lymphocytes at mitosis was examined. Cells of the same donor were irradiated with 990 MeV/n Fe-ions (LET = 155 keV/?m), 200 MeV/n Fe-ions (LET = 440 keV/?m) and X-rays and aberrations were measured in first cycle mitoses harvested at different times after 48 84 h in culture and in prematurely condensed G2-cells (PCCs) collected at 48 h using calyculin A. Analysis of the time-course of chromosomal damage in first cycle metaphases revealed that the aberration frequency was similar after X-ray irradiation, but increased two and seven fold after exposure to 990 and 200 MeV/n Fe-ions, respectively. Consequently, RBEs derived from late sampling times were significantly higher than those obtained at early times. The PCC-data suggest that the delayed entry of heavily damaged cells into mitosis results especially from a prolonged arrest in G2. Preliminary data obtained for 4.1 MeV/n Cr-ions (LET = 3160 keV/?m) revealed, that these delays are even more pronounced for low energy Fe-like particles. Additionally, for the different radiation qualities, BrdU-labeling indices and apoptotic indices were determined at several time-points. Only the exposure to low energy Fe-like particles affected the entry of lymphocytes into S-phase and generated a significant apoptotic response indicating that under this particular exposure condition a large proportion of heavily damaged cells is rapidly eliminated from the cell population. The significance of this observation for the estimation of the health risk associated with space radiation remains to be elucidated.
Radiation Response of a 9 Cr Oxide Dispersion Strengthened Steel to Heavy Ion Irradiation
Allen, Todd R. [University of Wisconsin, Madison; Gan, J. [Idaho National Laboratory (INL); Cole, James I. [Idaho National Laboratory (INL); Miller, Michael K [ORNL; Busby, Jeremy T [ORNL; Ukai, S. [Japan Atomic Energy Agency (JAEA); Shutthanandan, S. [Pacific Northwest National Laboratory (PNNL); Thevuthasan, S. [Pacific Northwest National Laboratory (PNNL)
Ferritic-martensitic (FM) alloys are expected to play an important role as cladding or structural components in Generation IV systems operating in the temperature range 350-700 C and to doses up to 200 dpa. Oxide dispersion strengthened (ODS) ferritic-martensitic steels have been developed to operate at higher temperatures than traditional FM steels. These steels contain nanometer-sized Y-Ti-O nanoclusters as a strengthening mechanism. Heavy ion irradiation has been used to determine the nanocluster stability over a temperature range of 500-700 C to doses of 150 dpa. At all temperatures, the average nanocluster size decreases but the nanocluster density increases. The increased density of smaller nanoclusters under radiation should lead to strengthening of the matrix. While a reduction in size under irradiation has been reported in some other studies, many report oxide stability. The data from this study are contrasted to the available literature to highlight the differences in the reported radiation response.
Transformation of multiwalled carbon nanotubes to amorphous carbon nanorods under ion irradiation
NASA Astrophysics Data System (ADS)
Honda, Shin-ichi; Tamura, Ryosuke; Nosho, Yusuke; Tsukagoshi, Akira; Niibe, Masahito; Terasawa, Mititaka; Hirase, Ryuji; Izumi, Hirokazu; Yoshioka, Hideki; Niwase, Keisuke; Taguchi, Eiji; Lee, Kuei-Yi; Oura, Masaki
Amorphous carbon nanorods were synthesized from hollow multiwalled carbon nanotubes (MWCNTs) by low-energy Ar ion irradiation at room temperature. The obtained nanorods were investigated by Raman spectroscopy, transmission electron microscopy (TEM), soft X-ray photoelectron spectroscopy (XPS), and soft X-ray absorption spectroscopy (XAS). It was found that the diameter of the MWCNTs significantly increased with increasing the fluence. Finally, the original hollow structure and the graphite (002) TEM diffraction spots of MWCNTs completely disappeared and a broadening of Raman spectra occurred, indicating the amorphization of MWCNTs. The increase in the diameter by the irradiation can be explained by the bending and the randomization of the broken carbon hexagonal networks, and the accumulation of knocked-on atoms. The XPS and XAS measurements also support the formation of amorphous carbon nanorods.
Effects of heavy ion irradiation on the thermodynamic and transport properties of YBCO
NASA Astrophysics Data System (ADS)
Luo, Xu; Leroux, Maxime; Mishra, Vivek; Ling, Xinsheng; Welp, Ulrich; Kwok, Wai-Kwong
The effects of Au heavy ion irradiation (HII) on the transport and thermodynamic properties of untwined YBCO crystals irradiated to dose matching fields of B? = 6 Tesla and 1 Tesla along the crystallographic c-axis were studied by angle resolved magnetoresistivtiy and high resolution AC specific heat measurements. Results from transport measurements confirm an enhancement in the ab-plane critical current for magnetic fields aligned along the columnar defects induced by HII. Surprisingly, specific heat measurements reveal a reduction in the thermodynamic upper critical field anisotropy of YBCO by about one half in the B? = 6T crystal. Moreover, for the B? = 1T crystal, we found the formation of an anomalous peak in the critical temperature near the direction of HII which may be associated with the Bose-glass transition. Work supported by Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.
Swift heavy ion irradiation of Pt nanocrystals: II. Structural changes and H desorption
Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C. (ANU)
The structural properties and H desorption from embedded Pt nanocrystals (NCs) following irradiation with swift heavy ions were investigated as a function of energy and fluence. From x-ray absorption near-edge spectroscopy analysis, Pt-H bonding was identified in NCs annealed in a forming gas (95% N{sub 2} + 5% H{sub 2}) ambient. The H content decreased upon irradiation and the desorption process was NC-size dependent such that larger NCs required a higher fluence to achieve a H-free state. Pt-H bonding and NC dissolution both perturbed the NC structural parameters (coordination number, bond-length and mean-square relative displacement) as determined with extended x-ray absorption fine structure measurements.
The behavior of rare-earth pyrochlores and perovskites under ion irradiation
NASA Astrophysics Data System (ADS)
Yudintsev, S. V.; Livshits, T. S.; Zhang, J.; Ewing, R. C.
The behavior of samples of A2B2O7 composition under irradiation with 1-MeV Kr2+ ions was studied (A is a simulator of the REE-actinide fraction of the wastes of the treatment of used nuclear fuel and B is a quadrivalent cation of Zr, Sn, or Ti). Depending on the B elements, the samples are crystallized either in pyrochlore (Zr and Sn) or in the perovskite structural type (Ti). The matrices of the pyrochlore structure are radiation-resistant, which is shown by their high critical doses and low critical temperatures of amorphization. The phases of monocline REE titanate structure are characterized by low irradiation resistance and should be amorphized even within centuries of storage. To characterize the possibilities of their usage as matrices for waste immobilization, synthesis of materials containing short-living actinides and studies of the degree of the amorphization effect on their stability in aqueous solutions are required.
Effect of gold ion irradiation on helium migration in fluoroapatites investigated with nuclear reaction analysis
NASA Astrophysics Data System (ADS)
Miro, S.; Studer, F.; Costantini, J.-M.; Berger, P.; Haussy, J.; Trouslard, P.; Grob, J.-J.
In the context of nuclear waste storage, the knowledge of the effect of irradiation on the diffusion of helium produced by ?-decays in apatites is an important issue. The analysis of implanted 3He diffusion for two compositions was carried out with the 3He(d,p)4He nuclear reaction by using a deuteron milli- or micro-beam. Upon 163-MeV Au-ion irradiation, a significant fraction of 3He atoms migrated towards the surface below which they were trapped, whereas a proportion of 3He atoms remained trapped in the end-of-range region. Moreover, a clear helium loss was determined. These radiation-induced migration effects are enhanced in Ca10(PO4)6F2 compared with the Ca4Nd6(SiO4)6F2.
Radiation blistering in inconel-625 due to 100 keV helium ion irradiation
NASA Astrophysics Data System (ADS)
Whitton, J. L.; Rao, A. S.; Kaminsky, M.
The objective of this study was to determine whether the change of angle of incidence of an ion beam impinging on surface blisters during their growth phase (before exfoliation) could influence the blister skin thickness and the blister crater depth. Polished, polycrystalline Inconel-625 samples were irradiated at room temperature and at normal incidence to the major sample surface with 100 keV helium ions to a total dose of 6.24 × 10 18 ions/cm 2. The results revealed that many exfoliated blisters leave craters which have two or three concentric pits. The blister skin thickness near the center of the blister was found to agree well with the calculated projected range of 100 keV He ions in nickel. However, the blister skin thickness of some exfoliated blisters along the edge of the fracture surface showed different thicknesses. A model is proposed to explain the observed blister crater/blister skin fracture features in terms of a change of angle of incidence of the incident ions to the surface during the growth phase of surface blisters.
Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions
NASA Technical Reports Server (NTRS)
Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.
We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.
Correlation between the Atomic Alignment and the Alignment of XeX* (B, C) Rotation in the Reactions of Oriented Xe (3P2, MJ = 2) + Halogen (X)-Containing Molecules
NASA Astrophysics Data System (ADS)
Ohoyama, H.; Yasuda, K.; Kasai, T.
The polarization of the XeX* (B) and XeX* (C) emissions in the reactions of oriented Xe* (3P2, MJ = 2) + halogen (X)-containing molecules (CCl4, CF3Br, CF3I, CH3I, NF3) has been measured as a function of each magnetic MJ' substate in the collision frame. The parallel polarization of the XeX* (B, C) emissions to the relative velocity vector is commonly observed for all magnetic MJ' substates. The correlation between the atomic alignment (MJ') and the MJ'-dependent alignment (AMJ') of the XeX* (B, C) rotation is found to be extremely different between the XeX* (B) and XeX* (C) channels: For XeX* (B), AMJ' is highest for the MJ' = 0 state, except CCl4, whereas the |MJ'| = 2 states give the highest AMJ' for XeX* (C). Alternatively, the correlation between the configuration (LZ') of the inner 5p orbital and the LZ'-dependent alignment (ALZ') of the XeX* (B, C) rotations is revealed. The collision with |LZ'| = 1 causes a similar positive alignment ALZ' for the XeX* (B) and XeX* (C) channels. The alignment ALZ' at the collision with |LZ'| = 0 is extremely different between the XeX* (B) and XeX* (C) channels. The collision with LZ' = 0 induces no alignment of XeX* (C) except CF3I, that is, ALZ'=0 ? 0, whereas it induces the higher positive ALZ' of XeX* (B). The different MJ' dependence on the alignment of the XeX* (B, C) rotation between the XeX* (B) and XeX* (C) channels can be recognized as the change of reaction mechanism due to the difference in the favorable impact parameter for each MJ' state between the XeX* (B) and XeX* (C) channels, which reflects the ?' conservation in the course of ion-pair (Xe+-RX-) formation.
Formation of CO_2 and OCS after cosmic ion irradiation of icy grain mantles
NASA Astrophysics Data System (ADS)
Palumbo, M. E.; Baratta, G.; Fulvio, D.; Garozzo, M.; Ioppolo, S.; Kanuchova, Z.; Leto, G.; Sangiorgio, I.; Strazzulla, G.
Molecules in the solid phase have been detected in the line of sight of quiescent molecular clouds and star forming regions as icy mantles on dust grains. Water (H_2O), carbon monoxide (CO), carbon dioxide (CO_2), methanol (CH_3OH), carbonyl sulfide (OCS), methane (CH_4), ammonia (NH_3) and sulfur dioxide (SO_2) are the most abundant observed species (e.g. Gibb et al. 2004). It is generally accepted that some of these species (such as CO) freeze out from the gas phase while others (such as water and methanol) are formed on grains after surface reactions (Ioppolo et al. 2008). CO_2 and OCS are not expected to freeze out from the gas phase and grain surface models do not account for their observed abundance (Ruffle & Herbst 2001; Garrod et al. 2007). It has been suggested that these molecules are formed after energetic processing (i.e. cosmic ion and UV irradiation) of icy grain mantles (d'Hendecourt et al. 1986; Moore et al. 1991; Palumbo & Strazzulla 1993; Ioppolo et al. 2009; Garozzo et al. 2010 ). Here we will present the results of laboratory experiments which show the formation of CO_2 and OCS after ion irradiation of relevant ice mixture at low temperature (10-20 K). We will also present the comparison between the profile of bands in laboratory spectra with those observed in space. We will show that laboratory spectra well reproduce the interstellar features and that the amount of carbon dioxide and carbonyl sulfide formed after ion irradiation can account for the observed amount towards molecular clouds.
4D particle therapy PET simulation for moving targets irradiated with scanned ion beams
NASA Astrophysics Data System (ADS)
Laube, K.; Menkel, S.; Bert, C.; Enghardt, W.; Helmbrecht, S.; Saito, N.; Fiedler, F.
Particle therapy positron emission tomography (PT-PET) allows for an in vivo and in situ verification of applied dose distributions in ion beam therapy. Since the dose distribution cannot be extracted directly from the ?+-activity distribution gained from the PET scan the validation is done by means of a comparison between the reconstructed ?+-activity distributions from a PT-PET measurement and from a PT-PET simulation. Thus, the simulation software for generating PET data predicted from the treatment planning is an essential part of the dose verification routine. For the dose monitoring of intra-fractionally moving target volumes the PET data simulation needs to be upgraded by using time resolved (4D) algorithms to account correctly for the motion dependent displacement of the positron emitters. Moreover, it has to consider the time dependent relative movement between target volume and scanned beam to simulate the accurate positron emitter distribution generated during irradiation. Such a simulation program is presented which properly proceeds with motion compensated dose delivery by scanned ion beams to intra-fractionally moving targets. By means of a preclinical phantom study it is demonstrated that even the sophisticated motion-mitigated beam delivery technique of range compensated target tracking can be handled correctly by this simulation code. The new program is widely based on the 3D PT-PET simulation program which had been developed at the Helmholtz-Zentrum Dresden-Rossendorf, Germany (HZDR) for application within a pilot project to simulate in-beam PET data for about 440 patients with static tumor entities irradiated at the former treatment facility of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany (GSI). A simulation example for a phantom geometry irradiated with a tracked 12C-ion beam is presented for demonstrating the proper functionality of the program.
HZE ??Fe-ion irradiation induces endothelial dysfunction in rat aorta: role of xanthine oxidase.
Soucy, Kevin G; Lim, Hyun Kyo; Kim, Jae Hyung; Oh, Young; Attarzadeh, David O; Sevinc, Baris; Kuo, Maggie M; Shoukas, Artin A; Vazquez, Marcelo E; Berkowitz, Dan E
Ionizing radiation has been implicated in the development of significant cardiovascular complications. Since radiation exposure is associated with space exploration, astronauts are potentially at increased risk of accelerated cardiovascular disease. This study investigated the effect of high atomic number, high-energy (HZE) iron-ion radiation on vascular and endothelial function as a model of space radiation. Rats were exposed to a single whole-body dose of iron-ion radiation at doses of 0, 0.5 or 1 Gy. In vivo aortic stiffness and ex vivo aortic tension responses were measured 6 and 8 months after exposure as indicators of chronic vascular injury. Rats exposed to 1 Gy iron ions demonstrated significantly increased aortic stiffness, as measured by pulse wave velocity. Aortic rings from irradiated rats exhibited impaired endothelial-dependent relaxation consistent with endothelial dysfunction. Acute xanthine oxidase (XO) inhibition or reactive oxygen species (ROS) scavenging restored endothelial-dependent responses to normal. In addition, XO activity was significantly elevated in rat aorta 4 months after whole-body irradiation. Furthermore, XO inhibition, initiated immediately after radiation exposure and continued until euthanasia, completely inhibited radiation-dependent XO activation. ROS production was elevated after 1 Gy irradiation while production of nitric oxide (NO) was significantly impaired. XO inhibition restored NO and ROS production. Finally, dietary XO inhibition preserved normal endothelial function and vascular stiffness after radiation exposure. These results demonstrate that radiation induced XO-dependent ROS production and nitroso-redox imbalance, leading to chronic vascular dysfunction. As a result, XO is a potential target for radioprotection. Enhancing the understanding of vascular radiation injury could lead to the development of effective methods to ameliorate radiation-induced vascular damage. PMID:21787183
Nanoindentation hardness and its extrapolation to bulk-equivalent hardness of F82H steels after single- and dual-ion beam irradiation
NASA Astrophysics Data System (ADS)
Takayama, Y.; Kasada, R.; Sakamoto, Y.; Yabuuchi, K.; Kimura, A.; Ando, M.; Hamaguchi, D.; Tanigawa, H.
The irradiation hardening behavior of reduced-activation ferritic steels after single Fe-ion beam irradiation and dual-ion (Fe ion and He ion) beam irradiation experiments was investigated with nanoindentation tests. The ion-irradiation experiments were conducted at 563 K with 6.4 MeV Fe3+ ions up to 3 dpa at a 600 nm depth from the irradiated surface. Furthermore, these experiments were conducted with and without simultaneous energy-degraded 1 MeV He+ ions up to 300 appm. The materials used were F82H, F82H + 1Ni, and F82H + 2Ni to investigate the effect of Ni addition on the irradiation hardening behavior. The measured nanoindentation hardness was converted to the bulk-equivalent hardness based on a combination of the Nix-Gao model to explain the indentation size effect and the composite hardness model to explain the softer substrate effect of the nonirradiated region beyond the irradiated depth range. It is clearly shown that the Ni addition enhances the irradiation hardening of F82H. The bulk-equivalent hardness is compared with the experimentally obtained Vickers hardness of F82H steels after neutron irradiation. The effect of simultaneously implanted helium on the irradiation hardening is negligible in the investigated irradiation conditions.
Heavy ion irradiation of Bi-2223 silver-clad tapes for superconducting current density enhancement
Malozcnoff, A.P.; Carter, W.L.; Riley, G.N. Jr. [American Superconductor Corp., Westborough, MA (United States); Wheeler, R. IV; Kirk, M.A. [Argonne National Lab., IL (United States); Civale, L.; Marwick, A.D. [IBM Research, Yorktown, NY (United States)
Silver-clad composite tapes of Bi(Pb)SrCaCuO-2223 were irradiated with 1 GeV Au{sup 23+} ions perpendicular to the tape plane, creating columnar tracks with 10 nm diameter. Detailed transmission electron microscopy shows continuous columns, but with variations in the track thickness of +/{minus}2 nm. Magnetic hystersis measurements show substantial enhancement of superconducting current density at most temperatures and fields. Granular and nongranular models for the origin of the magnetic signals are discussed. The results indicate the potential for further performance improvement in high temperature superconducting wire technology, as well as limits in the high-field performance at 77 K.
Nanostructuring of high-TC superconductors via masked ion irradiation for efficient ordered vortex pinning
NASA Astrophysics Data System (ADS)
Trastoy, J.; Rouco, V.; Ulysse, C.; Bernard, R.; Faini, G.; Lesueur, J.; Briatico, J.; Villegas, J. E.
We studied vortex dynamics in a YBa2Cu3O7-? thin film with two different sources of pinning: intrinsic random defects and an artificial square array of defects created by masked ion irradiation. We study commensurability effects between the vortex lattice and the pinning array as a function of the vortex velocity v and the temperature. We find that at low temperatures the commensurability effects (magneto-resistance drop at the matching fields) are stronger at low velocities, in contrast with the behavior previously observed in low-critical-temperature superconductors.
Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission
McKenna, P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Carroll, D. C.; Ledingham, K. W. D.; McCanny, T.; Robson, L. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Clarke, R. J.; Neely, D.; Robinson, A. P. L. [CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Evans, R. G. [CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Department of Physics, Imperial College, London, SW7 2AZ (United Kingdom); Lindau, F.; Lundh, O.; Wahlstroem, C.-G. [Department of Physics, Lund University, P.O. Box 118, S-22100 Lund (Sweden); Simpson, P. T.; Zepf, M. [Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN (United Kingdom)
An experimental investigation of lateral electron transport in thin metallic foil targets irradiated by ultraintense ({>=}10{sup 19} W/cm{sup 2}) laser pulses is reported. Two-dimensional spatially resolved ion emission measurements are used to quantify electric-field generation resulting from electron transport. The measurement of large electric fields ({approx}0.1 TV/m) millimeters from the laser focus reveals that lateral energy transport continues long after the laser pulse has decayed. Numerical simulations confirm a very strong enhancement of electron density and electric field at the edges of the target.
Distribution of hydrogen peroxide-dependent reaction in a gelatin sample irradiated by carbon ion beam.
Matsumoto, Ken-ichiro; Aoki, Ichio; Nakanishi, Ikuo; Matsumoto, Atsuko; Nyui, Minako; Endo, Kazutoyo; Anzai, Kazunori
We investigated the amount and distribution of hydrogen peroxide (H(2)O(2)) generated in a solid gelatin sample irradiated by heavy ion (carbon) beam. We irradiated the gelatin sample, which contained a nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, TEMPOL), with a 290-MeV/nucleon carbon beam (~128 Gy). To verify the distribution of H(2)O(2) generation in the irradiated sample, we employed both electron paramagnetic resonance (EPR) spectroscopic and magnetic resonance (MR) imaging methods based on H(2)O(2)-dependent paramagnetic loss of TEMPOL. We obtained a distribution profile of the H(2)O(2)-dependent reaction in the gelatin sample when we irradiated gelatin samples with carbon beams with several different linear energy transfer (LET) values. Because the profiles of oxygen consumption in the gelatin sample measured by L-band EPR oxymetry and of the H(2)O(2)-dependent reaction have almost the same shape, the profile of the H(2)O(2)-dependent reaction can be used as an estimation of the profile of the generation of H(2)O(2). The H(2)O(2) profile in one intact gelatin sample scanned by 7-tesla MR imaging showed a similar shape as a result of the EPR experiment. We obtained several hundreds of micromolars of H(2)O(2) generated in a gelatin sample irradiated by carbon beam when 200 Gy was given at the surface of the sample. H(2)O(2) distribution was almost flat, with only a slight peak just before the end of the beam. PMID:20885086
Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties
McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor [Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, Washington 99352 (United States)] [Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, Washington 99352 (United States); Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States)] [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States); Burks, Edward C.; Liu, Kai [Department of Physics, University of California, Davis, California 95616 (United States)] [Department of Physics, University of California, Davis, California 95616 (United States)
A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NCs) of Fe core-Fe{sub 3}O{sub 4} shell or fully oxidized Fe{sub 3}O{sub 4}. Films of these NC on Si(100) or MgO(100)/Fe{sub 3}O{sub 4}(100) were irradiated to 10{sup 16} Si{sup 2+}/cm{sup 2} near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the NC films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.
Analysis of the sub-cascade structure in copper produced by ion irradiations
NASA Astrophysics Data System (ADS)
Ishida, I.; Sasaki, S.; Yoshiie, T.; Iwase, A.; Iwata, T.; Kiritani, M.
The sub-cascade structure has been investigated by analyzing the SFTs (stacking fault tetrahedra) observed with transmission electron microscopy in thin foil copper. In specimens irradiated by ions of various species and energies at room temperature, grouped SFTs were observed, and the number of grouped SFTs increased with maximum PKA (primary knock-on atom) energy. Considering the PKA energy spectrum, the damage energy, and a SFT formation model corresponding to sub-cascades, the number density of SFTs and the distributions of the number of grouped SFTs were analyzed and consistently explained. The effect of successive cascade formation along the ion trace on apparent sub-cascade image formation was estimated by analyses of the spacing of successive cascades and their occurrence probability.
Synthesis of polymer ion-exchange hydrogels under ? - irradiation 60Co
NASA Astrophysics Data System (ADS)
Le, V. M.; Zhevnyak, V. D.; Pak, V. Kh; Ananev, V. A.; Borodin, U. V.
We have reported earlier about the modification of ion-exchange hydrogel under the influence of gamma radiation. The optimal absorbed dose of irradiation had been choosen for radiation modification of polymer hydrogels by ionits to produce products with a high content of the gel - fractions and sufficient mechanical properties. The dependence of the static exchange capacity of hydrogels on the type of ionit and its fractional composition had been studied. The dependence of the static exchange capacity of the quantitative composition of the ionit in the volume of the hydrogel had been investigated. The ion-exchange medical eye lenses had been made under selected conditions of synthesis. Their sorption properties had been studied.
Image printing on the surface of anti-biofouling zwitterionic polymer brushes by ion beam irradiation.
Kitano, Hiromi; Suzuki, Hisatomo; Kondo, Takuya; Sasaki, Kenta; Iwanaga, Shintaroh; Nakamura, Makoto; Ohno, Kohji; Saruwatari, Yoshiyuki
A CMB monomer was polymerized on a glass plate with a surface-confined ATRP initiator containing a 2-bromoisobutyryl group. The glass plate modified with a PCMB brush was highly hydrophilic and showed a strong resistance against non-specific adsorption of proteins and cell adhesion. Upon ion beam irradiation, furthermore, the PCMB brush was ablated and a hollow space with a designed shape could be made to which HEK293 cells (from human embryonic kidney) and Hep G2 (from human hepatoma) cells non-specifically adhered, while no adhesion of these cells to the non-treated area on the brush was observed. The present results clearly indicate the usefulness of ion beam-printed patterns of anti-biofouling zwitterionic polymer brushes in the biomedical field. PMID:21243650
SAXS Analysis of Embedded Pt Nanocrystals Irradiated with Swift Heavy Ions
Giulian, R.; Kluth, P.; Sprouster, D. J.; Araujo, L. L.; Byrne, A. P.; Ridgway, M. C. [Research School of Physical Sciences and Engineering, Australian National University (Australia); Cookson, D. J. [Australian Synchrotron Research Program, Argone, IL (United States)
Elongated Pt nanocrystals (NCs) formed in SiO{sub 2} by ion implantation, thermal annealing and swift heavy ion irradiation were analyzed by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. Transmission SAXS measurements were performed in samples aligned at different angles relative to the photon beam resulting in non-isotropic scattering and thus enabling the three dimensional analysis of the NCs. Selected angular sectors of the detector were integrated and analyzed separately, leading to the individual evaluation of both the major and minor dimensions of the rod-shaped NCs. This method enables the use of well established spherical models for the SAXS data analysis and yielded excellent agreement with TEM results.
Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils
Buchowicz, G.; Stone, P.R.; Robinson, J.T.; Cress, C.D.; Beeman, J.W.; Dubon, O.D.
Graphene grown by chemical vapor deposition and supported on SiO2 and sapphire substrates was studied following controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra following fluences ranging from 1012 cm-2 to 1015 cm-2 indicate that the structure of graphene evolves from a highly-ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by orders of magnitude while, remarkably, the Hall concentration remains almost unchanged, suggesting that the Fermi level is pinned at a hole concentration near 1x1013 cm-2. A model for scattering by resonant scatterers is in good agreement with mobility measurements up to an ion fluence of 1x1014 cm-2.
Control of magnetic properties of MnBi and MnBiCu thin films by Kr+ ion irradiation
NASA Astrophysics Data System (ADS)
Xu, Qianqian; Kanbara, Ryutarou; Kato, Takeshi; Iwata, Satoshi; Tsunashima, Shigeru
Mn52Bi48 (15 nm) and Mn54Bi24Cu21 (15 nm) thin films were prepared by the magnetron sputtering and vacuum annealing at 350 °C, and the variations of their structures and magnetic properties with 30 keV Kr+ ion irradiation were studied. The MnBi and MnBiCu films exhibited saturation magnetizations Ms of 180 emu/cc and 210 emu/cc, the coercivities Hc of 10 kOe and 3.4 kOe, respectively. The Ms and Hc of the MnBi abruptly vanished by the irradiation of ion dose at 3 × 1014 ions/cm2, while those of the MnBiCu film gradually decreased with increasing the ion dose and became zero at 5 × 1013 ions/cm2. The different trend on the ion irradiation between MnBi and MnBiCu films is understood by the surface structure of the film, i.e., the MnBi has convex islands on its surface, which protect the underneath NiAs-type MnBi from the irradiation, while the MnBiCu has rather flat surface, and its crystal structure was uniformly modified by the irradiation. From the surface flatness and the uniformity of the MnBiCu film, as well as the low annealing temperature of 350 °C, it was concluded that the MnBiCu film is one of the attractive materials for high-density ion irradiation bit patterned media.
Interplay of energy dissipation, ion-induced mixing, and crystal structure recovery, and surface effects in ion-irradiated magnetic Fe/Cr/Fe trilayers
NASA Astrophysics Data System (ADS)
Brodyanski, A.; Blomeier, S.; Gnaser, H.; Bock, W.; Hillebrands, B.; Kopnarski, M.; Reuscher, B.
The influence of the ion irradiation by 30 keV Ga+ ions on the crystal structure, chemical ordering, magnetic properties, and topography of epitaxial Fe/Cr/Fe trilayers was investigated by different analytical techniques. We present direct experimental evidence, supported by theoretical estimates, that two processes take place concurrently due to the Ga-ion implantation. (i) A complete atom mixing of the Cr atoms within the Fe multilayers is occurring due to the collision cascades during the ballistic regime, and (ii) an essentially complete recovery of the initial single-crystal quality of the Fe multilayers by healing the melted and damaged area through the thermal spike phase occurs. Based on the experimental range distributions and theoretical modeling, channeling of Ga+ ions in the experiments is found to contribute weakly to ion penetration and stopping, and the relative fraction of the well-channeled ions is marginally small. On the other hand, this weak channeling is sufficient to reduce the sputter yield by a factor of more than 5 in comparison with the sputtering of polycrystalline samples, evidence for the fact that the magnitude of channeling is not of primary importance for the sputtering. We offer an explanation for the observation of dramatic and abrupt changes in the surface roughness with increasing fluences in terms of a transformation from a single-phase single-crystal implanted region (bcc-Fe) to a mixture of the polycrystalline ?-Fe-like bcc and ?-Fe3Ga structures within the outer half of the original Fe/Cr/Fe trilayer at fluences above 6.25 × 1016 ion/cm2. The wall-like elevations appearing at the boundary of the irradiated areas were analyzed experimentally by varying the irradiation conditions. We showed that the wall size is governed by the ion-current density applied. A physical explanation for the appearance of such topographic features is presented, which would be valid for any material irradiated by a focused ion beam.
Temperature-dependent Void Formation and Growth At Ion-irradiated Nanocrystalline CeO2–Si Interfaces
Perez-Bergquist, Alejandro G.; Zhang, Yanwen; Varga, Tamas; Moll, Sandra; Namavar, Fereydoon; Weber, William J.
Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria, due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self?heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to ~ 4 × 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0 to 1.5 MeV), and at varying temperatures (160?600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiationinduced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.
Size-dependent radiation tolerance and corrosion resistance in ion irradiated CrN/AlTiN nanofilms
NASA Astrophysics Data System (ADS)
Hong, Mengqing; Ren, Feng; Wang, Yongqiang; Zhang, Hongxiu; Xiao, Xiangheng; Fu, Dejun; Yang, Bing; Jiang, Changzhong
This paper demonstrates a substantial enhancement in radiation tolerance and corrosion resistance for the CrN/AlTiN multilayered nanofilms with the decreasing of period-thickness. After irradiation by 190 keV Ar+ ions to the dose of 81 dpa, the amorphization region in the CrN/AlTiN 3 nm multilayered nanofilm is much smaller than that in the CrN/AlTiN 7 nm multilayered nanofilm and the CrN film based on glancing-incidence X-ray diffraction measurements. Potentiodynamic polarization and impedance measurements show that the CrN/AlTiN multilayered nanofilms have good corrosion resistance to irradiation. With increasing the irradiation fluence, the irradiated samples are more susceptible to corrosive electrolyte. However, the CrN/AlTiN multilayered nanofilm with smaller period-thickness shows significant enhancement of the corrosion resistance under both irradiation and un-irradiation conditions. Under the same irradiation fluence of 5 × 1016 ions/cm2, the corrosion current density increased 9.47 times for the CrN film, while it only increased 2.08 times for the CrN/AlTiN 3 nm multilayered nanofilm. The interfaces of multilayered nanofilms act as effective sinks for irradiation-induced defects and are responsible for the enhanced radiation tolerance and corrosion resistance properties.