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K(alpha) X-ray Emission Spectra from Highly Charged Fe Ions in EBIT
Jacobs, V; Beiersdorfer, P
A detailed spectral model has been developed for the computer simulation of the 2p {yields} 1s K{alpha} X-ray emission from highly charged Fe ions in the Electron Beam Ion Trap (EBIT). The spectral features of interest occur in the range from 1.84 {angstrom} to 1.94 {angstrom}. The fundamental radiative emission processes associated with radiationless electron capture or dielectronic recombination, inner-shell electron collisional excitation, and inner-shell electron collisional ionization are taken in account. For comparison, spectral observations and simulations for high-temperature magnetic-fusion (Tokamak) plasmas are reviewed. In these plasmas, small departures from steady-state corona-model charge-state distributions can occur due to ion transport processes, while the assumption of equilibrium (Maxwellian) electron energy distributions is expected to be valid. Our investigations for EBIT have been directed at the identification of spectral features that can serve as diagnostics of extreme non-equilibrium or transient-ionization conditions, and allowance has been made for general (non-Maxwellian) electron energy distributions. For the precise interpretation of the high-resolution X-ray observations, which may involve the analysis of blended spectral features composed of many lines, it has been necessary to take into account the multitude of individual fine-structure components of the K{alpha} radiative transitions in the ions from Fe XVIII to Fe XXV. At electron densities higher than the validity range of the corona-model approximation, collisionally induced transitions among low-lying excited states can play an important role. It is found that inner-shell electron excitation and ionization processes involving the complex intermediate ions from Fe XVIII to Fe XXI produce spectral features, in the wavelength range from 1.89 {angstrom} to 1.94 {angstrom}, which are particularly sensitive to density variations and transient ionization conditions.
THE DIFFERENCE IN NARROW Fe K{alpha} LINE EMISSION BETWEEN SEYFERT 1 AND SEYFERT 2 GALAXIES
Liu Teng; Wang Junxian, E-mail: firstname.lastname@example.com, E-mail: email@example.com [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China (China)
We compile a sample of 89 Seyfert galaxies with both [O IV] 25.89 {mu}m line luminosities observed by Spitzer IRS and X-ray spectra observed by XMM-Newton EPIC. Using [O IV] emission as a proxy for active galactic nucleus (AGN) intrinsic luminosity, we find that although type 2 AGNs have higher line equivalent widths, the narrow Fe K{alpha} lines in Compton-thin and Compton-thick Seyfert 2 galaxies are 2.9{sup +0.8}{sub -0.6} and 5.6{sup +1.9}{sub -1.4} times weaker in terms of luminosity than Seyfert 1 galaxies, respectively. This indicates that different correction factors need to be applied for various types of AGNs before the narrow Fe K{alpha} line luminosity could serve as an intrinsic AGN luminosity indicator. We also find that Seyfert 1 galaxies in our sample have on average marginally larger line widths and higher line centroid energies, suggesting contamination from highly ionized Fe line or broader line emission from much smaller radius, but this effect is too weak to explain the large difference in narrow Fe K{alpha} line luminosity between type 1 and type 2 AGNs. This is the first observational evidence showing that the narrow Fe K{alpha} line emission in AGNs is anisotropic. The observed difference is consistent with theoretical calculations assuming a smoothly distributed obscuring torus and could provide independent constraints on the clumpiness of the torus.
Structure of the Co and FeK alpha(3,4) Satellite Spectra
Daimant,R.; Sharon, R.; Caliebe, W.; Kao, C.; Deutsch, M.
The K{alpha}{sub 3,4} satellite spectra, originating in the [1s2p]{sup -1}{yields} [2p]{sup -2} transition, were measured with high resolution for Co and Fe, using photoexcitation by tunable monochromatized synchrotron radiation. Fits to a phenomenological sum of Voigt functions and to ab initio relativistic Dirac-Fock-calculated spectra resolved the structure underlying the spectra. The dependence of the satellites' intensity on the excitation energy yielded accurate values for the excitation thresholds. The shake-theory-based Thomas model was found to deviate from the measured intensities, indicating near-threshold major contributions from non-shake excitation processes, such as the knockout, or 'two step one,' effect.
XMM-Newton Observation of Fe K(alpha) Emission from a BAL QSO: Mrk 231
NASA Technical Reports Server (NTRS)
Turner, T. J.; Kraemer, S. B.
We present results from a 20 ksec XMM-Newton observation of Mrk 231. EPIC spectral data reveal strong line emission due to Fe K alpha, which has rarely been detected in this class, as BAL QSOs are very faint in the X-ray band. The line energy is consistent with an origin in neutral Fe. The width of the line is equivalent to a velocity dispersion approximately 18,000 kilometers per second and thus the line may be attributed to transmission and/or reflection from a distribution of emitting clouds. If, instead, the line originates in the accretion disk then the line strength and flat X-ray continuum support some contribution from a reflected component, although the data disfavor a model where the hard X-ray band is purely reflected X-rays. The line parameters are similar to those obtained for the Fe Ka line detected in another BAL QSO, H1413 + 117.
Iron K-alpha Emission from a Decaying Magnetar Model of Gamma-Ray Bursts
M. J. Rees; P. Meszaros
The recent report of X-ray Fe features in the afterglow of the gamma-ray burst GRB 991216 may provide important clues for identifying the nature of its progenitor and constraining the burst mechanism. We argue that the strong line emission can be attributed to the interaction of a continuing (but decaying) post-burst relativistic outflow from the central engine with the progenitor stellar envelope at distances less than a light-hour. Only a small mass of Fe is then required, which could have been readily produced by the star itself.
The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron K$\\alpha$ line
Marinucci, A; Bianchi, S; Lu, T N; Arevalo, P; Balokovi?, M; Ballantyne, D; Bauer, F E; Boggs, S E; Christensen, F E; Craig, W W; Gandhi, P; Hailey, C J; Harrison, F; Puccetti, S; Rivers, E; Walton, D J; Stern, D; Zhang, W
We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suzaku, BeppoSAX, Chandra and Swift. Simultaneous NuSTAR and Swift broad band spectra (in the 3-80 keV range) indicate a cutoff energy $E_{\\rm c}>210$ keV, with no detectable contribution from Compton reflection. NGC 2110 is one of the very few sources where no evidence for distant Compton thick scattering is found and, by using temporal information collected over more than a decade, we investigate variations of the iron K$\\alpha$ line on time scales of years. The Fe K$\\alpha$ line is likely the sum of two components: one constant (originating from distant Compton-thick material) and the other one variable and linearly correlated with the source flux (possibly arising from Compton-thin material much closer to the black h...
High-resolution measurements of the K-alpha spectra of low-ionizationm species of iron: A new spectral signature of nonequilibrium ionization conditions in young supernova remnants
NASA Technical Reports Server (NTRS)
Decaux, V.; Beiersdorfer, P.; Osterheld, A.; Chen, M.; Kahn, S. M.
We present the first systematic laboratory measurements of high-resolution K-alpha spectra of intermediate ions of iron, Fe X-XVII. These lines are not produced in collisional equilibrium plasmas because of the relevant charge states cannot exist at the high electron temperatures required for appreciable excitation of the K-alpha transitions. However, they can provide excellent spectral diagnostics for nonequilibrium ionization conditions, such the ionizing plasmas of young supernova remnants. To facilitate the line identifications, we compare our spectra with theoretical atomic calculations performed using multiconfiguration parametric potential and Dirac-Fock atomic codes. Our measurements also allow direct comparison with time-dependent ionization balance calculations for ionizing plasmas, and good agreement is found.
The role of hot electron refluxing in laser-generated K-alpha sources
Neumayer, P. [ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); FIAS Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main (Germany); Goethe Universitaet Frankfurt am Main, 60325 Frankfurt am Main (Germany); Aurand, B. [ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Johannes Gutenberg Universitaet Mainz, 55099 Mainz (Germany); Basko, M. [Institute for Theoretical and Experimental Physics, 117218 Moscow (Russian Federation); Goethe Universitaet Frankfurt am Main, 60325 Frankfurt am Main (Germany); Ecker, B. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institut Jena, 07743 Jena (Germany); Johannes Gutenberg Universitaet Mainz, 55099 Mainz (Germany); Gibbon, P.; Karmakar, A. [ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Institute for Advanced Simulation, Juelich Supercomputing Center, Forschungzentrum Juelich GmbH, 52425 Juelich (Germany); Hochhaus, D. C. [ExtreMe Matter Inst. EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Goethe Univ. Frankfurt am Main, 60325 Frankfurt am Main (Germany); Kazakov, E. [RRC Kurchatov Inst., 123182 Moscow (Russian Federation); Kuehl, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Johannes Gutenberg Univ. Mainz, 55099 Mainz (Germany); Labaune, C. [LULI, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Rosmej, O. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Tauschwitz, An. [ExtreMe Matter Inst. EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Goethe Univ. Frankfurt am Main, 60325 Frankfurt am Main (Germany)
A study of the contribution of refluxing electrons in the production of K-alpha radiation from high-intensity laser irradiated thin targets has been performed. Thin copper foils both freestanding, and backed by a thick substrate were irradiated with laser pulses of energies around 100 J at intensities ranging from below 10{sup 17} to above 10{sup 19} W/cm{sup 2}. At high laser intensities we find a strong reduction in the K-alpha yield from targets backed by the substrate. The observed yield reduction is in good agreement with a simple model using hot electron spectra from particle-in-cell simulations or directly inferred from the measured bremsstrahlung emission and can therefore be interpreted as due to the suppression of hot electron refluxing. The study shows that refluxing electrons play a dominant role in high-intensity laser driven K- alpha generation and have to be taken into account in designing targets for laser driven high-flux K-alpha sources.
Diffuse emission and pathological Seyfert spectra
NASA Technical Reports Server (NTRS)
Halpern, Jules P.
In this annual ROSAT status report, the diffuse emission and spectra from Seyfert galaxies are examined. Three papers are presented and their contents include the soft x-ray properties and spectra of a binary millisecond pulsar, the PSPC and HRI observations of a Starburst/Seyfert 2 Galaxy, and an analysis of the possibility of x-ray luminous starbursts in the Einstein Medium Sensitivity Survey.
Engineering upconversion emission spectra using plasmonic nanocavities.
Lantigua, Christopher; He, Sha; Bouzan, Milad Akhlaghi; Hayenga, William; Johnson, Noah J J; Almutairi, Adah; Khajavikhan, Mercedeh
We show that the upconversion emission spectra of Tm�? and Yb�? codoped ?-NaYF?-NaYF? core-shell nanoparticles can be judiciously modified by means of plasmonic nanocavities. Our analysis indicates that more than a 30-fold increase in conversion efficiency to the UV spectral band can be expected by engineering the NIR absorption and the local density of states. The effect of the nanocavity on the resulting radiation patterns is discussed. Our results are exemplified in cylindrical cavity geometries. PMID:24978717
12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments
Kugland, N; Constantin, C G; Niemann, C; Neumayer, P; Chung, H; Doppner, T; Kemp, A; Glenzer, S H; Girard, F
A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.
Comparison of experimental and simulated K{alpha} yield for 400 nm ultrashort pulse laser irradiation
Khattak, F. Y.; Percie du Sert, O. A. M. B.; Riley, D.; Foster, P. S.; Divall, E. J.; Hooker, C. J.; Langley, A. J.; Smith, J.; Gibbon, P. [School of Mathematics and Physics, Queen's University of Belfast, University Road, Belfast BT7 1NN (United Kingdom); Central Laser Facility, CLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); John von Neumann Institute for Computing, Central Institute for Applied Mathematics (ZAM), Computer Simulations Division, Research Centre Juelich, D-52425 Juelich (Germany)
Ti K{alpha} emission yields from foils irradiated with {approx}45 fs, p-polarized pulses of a frequency-doubled Ti:sapphire laser are presented. A simple model invoking vacuum heating to predict absorption and hot electron temperature was coupled with the cross section for K-shell ionization of Ti and the Bethe-Bloch stopping power equation for electrons. The peak predicted K{alpha} emission was in generally good agreement with experiment. This contrasts strongly with previous work at the fundamental frequency. Similar predictions using particle-in-cell (PIC) code simulation to estimate the number and temperature of hot electrons also gave good agreement for yield.
Extraction Of Emissivities From Thermal Infrared Spectra
NASA Technical Reports Server (NTRS)
Hook, Simon J.; Kahle, Anne B.
Report presents evaluation of two techniques for processing multispectral data. One technique for extraction of emissivity data called "model emittance calculation." Other technique called "thermal log residuals."
Retrieval of constituent mixing ratios from limb thermal emission spectra
NASA Technical Reports Server (NTRS)
Shaffer, William A.; Kunde, Virgil G.; Conrath, Barney J.
An onion-peeling iterative, least-squares relaxation method to retrieve mixing ratio profiles from limb thermal emission spectra is presented. The method has been tested on synthetic data, containing various amounts of added random noise for O3, HNO3, and N2O. The retrieval method is used to obtain O3 and HNO3 mixing ratio profiles from high-resolution thermal emission spectra. Results of the retrievals compare favorably with those obtained previously.
On the importance of satellite lines to the He-like K ALPHA complex and the G ratio for calcium, iron, and nickel
J. Oelgoetz; C. J. Fontes; H. L. Zhang; S. N. Nahar; A. K. Pradhan
New, more detailed calculations of the emission spectra of the He-like K ALPHA complex of calcium, iron and nickel have been carried out using data from both distorted-wave and R-matrix calculations. The value of the GD ratio (an extended definition of the G ratio that accounts for the effect of resolved and unresolved satellite lines) is significantly enhanced at temperatures below the temperature of He-like maximum abundance. Furthermore it is shown that satellite lines are important contributors to the GD ratio such that GD/G>1 at temperatures well above the temperature of maximum abundance. These new calculations demonstrate, with an improved treatment of the KLn (n>=3) satellite lines, that K ALPHA satellite lines need to be included in models of He like spectra even at relatively high temperatures. The excellent agreement between spectra and line ratios calculated from R-matrix and distorted-wave data also confirms the validity of models based on distorted-wave data for highly charged systems, provided the effect of resonances are taken into account as independent processes.
AO14: Detection of Aircraft Emission Signatures in Atmospheric Spectra
Oxford, University of
aircraft efficiency) and so a study of the impact of aircraft engine emissions is highly relevant and alsoAO14: Detection of Aircraft Emission Signatures in Atmospheric Spectra Supervisors: Dr A. Dudhia, Dr C. Piccolo Candidate Number: 26912 Abstract Commercial jet aircraft are known to have both
SMM observations of K-alpha radiation from fluorescence of photospheric iron by solar flare X-rays
NASA Technical Reports Server (NTRS)
Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Wolfson, C. J.; Acton, L. W.; Phillips, K. J. H.; Dennis, B. R.
High-resolution Fe K-alpha spectra near 1.94 A observed during solar flares with the Bent Crystal Spectrometer on the Solar Maximum Mission are presented. The evidence for two possible excitation mechanisms, electron impact and fluorescence, is examined. It is found that the fluorescence mechanism satisfactorily describes the results, while the observations do not support electron collisional excitation of the Fe K-alpha transitions in low ionization stages (II-XII) of iron. Using Bai's model of the fluorescent excitation process, the photospheric iron abundance relative to that of hydrogen is estimated to be 5-6 x 10 to the -5th. The mean height of the soft X-ray source producing the K-alpha fluorescence is calculated on the basis of this model for about 40 large flares. The solar K-alpha lines are found to be about 25 percent wider than those measured in the laboratory. Weak line features observed at wavelengths shorter than that of the K-alpha lines are discussed.
Spreadsheet-Based Program for Simulating Atomic Emission Spectra
ERIC Educational Resources Information Center
Flannigan, David J.
A simple Excel spreadsheet-based program for simulating atomic emission spectra from the properties of neutral atoms (e.g., energies and statistical weights of the electronic states, electronic partition functions, transition probabilities, etc.) is described. The contents of the spreadsheet (i.e., input parameters, formulas for calculating�
Fluorescence emission spectra of plant leaves and plant constituents
M. Lang; F. Stober; H. K. Lichtenthaler
Summary The UV-B radiation (e.g. 337 nm) induced blue fluorescence (BF) and red chlorophyll fluorescence spectra (RF) of green leaves from plants with different leaf structure were determined and the possible nature and candidates of the blue fluorescence emission investigated. The blue fluorescence BF is characterized by a main maximum in the 450 nm region and in most cases by
Analysis of far-infrared emission Fourier transform spectra
NASA Technical Reports Server (NTRS)
Park, J. H.; Carli, B.
An analysis method that uses the nonlinear least-squares fit technique has been developed for emission spectra obtained with a Fourier transform spectrometer. This method is used for the analysis of submillimeter-region atmospheric emission spectra obtained with a balloon-borne FT spectrometer that was carried out as a correlative measurement for the Limb IR Monitor of the Stratosphere (LIMS) satellite experiment. The retrieved mixing ratios of H2O and O3 in the stratosphere from four spectral intervals have standard deviations of about 10 percent, and the average values agree to within 10 percent of corresponding results from the LIMS satellite experiment which used a broadband emission radiometer in the IR region.
Uniting the Quiescent Emission and Burst Spectra of Magnetar Candidates
Yujin E. Nakagawa; Atsumasa Yoshida; Kazutaka Yamaoka; Noriaki Shibazaki
Spectral studies of quiescent emission and bursts of magnetar candidates using XMM-Newton, Chandra and Swift data are presented. Spectra of both the quiescent emission and the bursts for most magnetar candidates are reproduced by a photoelectrically absorbed two blackbody function (2BB). There is a strong correlation between lower and higher temperatures of 2BB (kT_LT and kT_HT) for the magnetar candidates of which the spectra are well reproduced by 2BB. In addition, a square of radius for kT_T (R_LT^2) is well correlated with a square of radius for kT_HT (R_HT^2). A ratio kT_LT/kT_HT ~ 0.4 is nearly constant irrespective of objects and/or emission types (i.e., the quiescent emission and the bursts). This would imply a common emission mechanism among the magnetar candidates. The relation between the quiescent emission and the bursts might be analogous to a relation between microflares and solar flares of the sun. Three AXPs (4U 0142+614, 1RXS J170849.0-400910 and 1E 2259+586) seem to have an excess above ~7 keV which well agrees with a non-thermal hard component discovered by INTEGRAL.
NSDL National Science Digital Library
Kaler, James B.
Spectra is a website illustrating how astronomers use spectra to understand what stars are made of, their structures, and their evolution. The page begins with an introduction to the electromagnetic spectrum and then goes into detail about the properties of light. Then it discusses how matter both creates and destroys radiation. It goes on to interpret absorption and emission lines. The website ends with discussing how astronomers use spectra to understand stars, galaxies, and other objects in the universe.
K{alpha} yields from Ti foils irradiated with ultrashort laser pulses
Riley, D.; Angulo-Gareta, J.J.; Khattak, F.Y.; Lamb, M.J.; Foster, P.S.; Divall, E.J.; Hooker, C.J.; Langley, A.J.; Clarke, R.J.; Neely, D. [School of Mathematics and Physics, Queen's University of Belfast, University Road, Belfast, BT7 1NN, Northern Ireland (United Kingdom); Central Laser Facility, CLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom)
We have studied the emission of K{alpha} radiation from Ti foils irradiated with ultrashort (45 fs) laser pulses. We utilized the fundamental (800 nm) light from a Ti:sapphire laser on bare foils and foils coated with a thin layer of parylene E (CH). The focusing was varied widely to give a range of intensities from approximately 10{sup 15}-10{sup 19} W cm{sup -2}. Our results show a conversion efficiency of laser to K{alpha} energy of {approx}10{sup -4} at tight focus for both types of targets. In addition, the coated targets exhibited strong secondary peaks of conversion at large defocus, which we believe are due to modification of the extent of preformed plasma due to the dielectric nature of the plastic layer. This in turn affects the level of resonance absorption. A simple model of K{alpha} production predicts a much higher conversion than seen experimentally and possible reasons for this are discussed.
A new scheme for multidimensional line transfer. II - ETLA method in one dimension with application to iron K-alpha lines
Castor, J.I.; Dykema, P.G.; Klein, R.I. (Lawrence Livermore National Laboratory, Livermore, CA (United States) Lawrence Livermore National Laboratory, Livermore, CA (United States) California, University, Berkeley (United States))
The 1D version of the radiation hydrodynamics computer code ALTAIR is discribed. It is an implementation of the equivalent two-level atom method, and also incorporates a variety of other iterative techniques to achieve a fast, accurate solution of the problem of coupled atomic kinetics and radiative transfer. All the techniques are described in sufficient detail to enable their use by others. The application of the program is illustrated by a set of calculations of the iron X-ray emission spectrum from intercloud hot gas that may exist in the broad-line region of active galactic nuclei. These calculations demonstrate that such spectra may be a rich load to mine for information about the hot gas in AGNs, and also that the concept of 'the iron K-alpha line' inadequately depicts the spectrum. 30 refs.
A new scheme for multidimensional line transfer. II - ETLA method in one dimension with application to iron K-alpha lines
NASA Technical Reports Server (NTRS)
Castor, John I.; Dykema, Pieter G.; Klein, Richard I.
The 1D version of the radiation hydrodynamics computer code ALTAIR is discribed. It is an implementation of the equivalent two-level atom method, and also incorporates a variety of other iterative techniques to achieve a fast, accurate solution of the problem of coupled atomic kinetics and radiative transfer. All the techniques are described in sufficient detail to enable their use by others. The application of the program is illustrated by a set of calculations of the iron X-ray emission spectrum from intercloud hot gas that may exist in the broad-line region of active galactic nuclei. These calculations demonstrate that such spectra may be a rich load to mine for information about the hot gas in AGNs, and also that the concept of 'the iron K-alpha line' inadequately depicts the spectrum.
Investigation of the Emission and Absorption Spectra of Water Vapor
NASA Astrophysics Data System (ADS)
Moskalenko, N. I.; Il'in, Yu. A.; Sadykov, M. S.
Emission and absorption spectra of water vapor are measured and analyzed for temperatures 350-2500 K in the spectral range 0.57-25 ?m. Based on the developed mathematical model of radiative transfer, the parameters of spectral transmission functions of N2O vapors are obtained at different temperatures. Practical application of the obtained radiative characteristics is considered for solving problems of radiative heat exchange in high-temperature media and designing optoelectronic systems intended for monitoring of aero carriers.
Superresolution Imaging of Multiple Fluorescent Proteins with Highly Overlapping Emission Spectra in Living Cells
Verkhusha, Vladislav V.
Superresolution Imaging of Multiple Fluorescent Proteins with Highly Overlapping Emission Spectra of geneti- cally encoded photoactivatable fluorescent probes with distinct emission spectra impedes photoactivatable far-red fluorescent protein, which facil- itates simultaneous imaging of three photoactivatable
Infrared emission spectra of candidate interstellar aromatic molecules
NASA Technical Reports Server (NTRS)
Schlemmer, S.; Balucani, N.; Wagner, D. R.; Steiner, B.; Saykally, R. J.
Interstellar dust is responsible, through surface reactions, for the creation of molecular hydrogen, the main component of the interstellar clouds in which new stars form. Intermediate between small, gas-phase molecules and dust are the polycyclic aromatic hydrocarbons (PAHs). Such molecules could account for 2-30% of the carbon in the Galaxy, and may provide nucleation sites for the formation of carbonaceous dust. Although PAHs have been proposed as the sources of the unidentified infrared emission bands that are observed in the spectra of a variety of interstellar sources, the emission characteristics of such molecules are still poorly understood. Here we report laboratory emission spectra of several representative PAHs, obtained in conditions approximating those of the interstellar medium, and measured over the entire spectral region spanned by the unidentified infrared bands. We find that neutral PAHs of small and moderate size can at best make only a minor contribution to these emission bands. Cations of these molecules, as well as much larger PAHs and their cations, remain viable candidates for the sources of these bands.
Terrestrial FeO Continuum Emission Observed in Sky Spectra
NASA Astrophysics Data System (ADS)
Slanger, Tom G.; Melchiorri, R.; Saran, D. V.
The terrestrial continuum emission in the visible spectral region has often been studied by both astronomers and aeronomers, in order to clarify backgrounds and the nature of the emissions. New observations from the ESI spectrograph on the Keck II telescope, as well as from the OSIRIS/Odin spectrograph and orbiter, have established that a major component of the emission originates with the FeO molecule [Evans et al., 2010]. This quasi-continuum peaks at 5950 A and extends from 5000 A well into the infrared. The identity has been demonstrated by comparison with meteor trains and laboratory measurements [Jenniskens et al., 2000]. Early studies of the continuum show consistency with the FeO emission as presently observed [Gadsden and Marovich, 1973]. Analysis of spectra from Kitt Peak [Neugent and Massey, 2010] demonstrates the great similarity between FeO emission in a clean atmosphere and high pressure sodium lamp emission in a polluted atmosphere. This research was supported by NSF Aeronomy under Grant ATM-0637433 . Evans, W.F.J., et al., Geophys. Res. Lett. [in press, 2010] Gadsden, M. and E. Marovich, J. Atm. Terr. Phys., 35, 1601-1614 [1973] Jenniskens, P., et al., Earth, Moon and Planets, 82-83, 429-434 [2000] Neugent, K.F. and P. Massey, PASP [in press, 2010
A K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging
Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej
K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source has an x-ray conversion efficiency of greater than 10?5 into K-alpha line emission. In preparation for phase contrast imaging applications, the size of the resultant K-alpha x-ray emission spot has been also characterized. The source exhibits sufficient spatial coherence to observe phase contrast. We observe a relatively small broadening of the K-alpha source size compared to the size of the laser beam itself. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented. PMID:20046807
Helium shells and faint emission lines from slitless flash spectra.
Bazin, Cyril; Koutchmy, Serge
At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen ? 4686�� line of the ionized helium HeII and in the neutral helium HeI line at 4713��. The extensions of these helium shells are typically 3�Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1�Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2�Mm and also around a prominence. PMID:25685435
Structural Effects of Oncogenic PI3K alpha Mutations
S Gabelli; C Huang; D Mandelker; O Schmidt-Kittler; B Vogelstein; L Amzel
Physiological activation of PI3K{alpha} is brought about by the release of the inhibition by p85 when the nSH2 binds the phosphorylated tyrosine of activated receptors or their substrates. Oncogenic mutations of PI3K{alpha} result in a constitutively activated enzyme that triggers downstream pathways that increase tumor aggressiveness and survival. Structural information suggests that some mutations also activate the enzyme by releasing p85 inhibition. Other mutations work by different mechanisms. For example, the most common mutation, His1047Arg, causes a conformational change that increases membrane association resulting in greater accessibility to the substrate, an integral membrane component. These effects are examples of the subtle structural changes that result in increased activity. The structures of these and other mutants are providing the basis for the design of isozyme-specific, mutation-specific inhibitors for individualized cancer therapies.
Emissivity spectra estimated with the MaxEnTES algorithm
NASA Astrophysics Data System (ADS)
Barducci, A.; Guzzi, D.; Lastri, C.; Nardino, V.; Pippi, I.; Raimondi, V.
Temperature and Emissivity Separation (TES) applied to multispectral or hyperspectral Thermal Infrared (TIR) images of the Earth is a relevant issue for many remote sensing applications. The TIR spectral radiance can be modeled by means of the well-known Planck's law, as a function of the target temperature and emissivity. The estimation of these target's parameters (i.e. the Temperature Emissivity Separation, aka TES) is hindered by the circumstance that the number of measurements is less than the unknown number. Existing TES algorithms implement a temperature estimator in which the uncertainty is removed by adopting some a priori assumption that conditions the retrieved temperature and emissivity. Due to its mathematical structure, the Maximum Entropy formalism (MaxEnt) seems to be well suited for carrying out this complex TES operation. The main advantage of the MaxEnt statistical inference is the absence of any external hypothesis, which is instead characterizes most of the existing the TES algorithms. In this paper we describe the performance of the MaxEnTES (Maximum Entropy Temperature Emissivity Separation) algorithm as applied to ten TIR spectral channels of a MIVIS dataset collected over Italy. We compare the temperature and emissivity spectra estimated by this algorithm with independent estimations achieved with two previous TES methods (the Grey Body Emissivity (GBE), and the Model Emittance Calculation (MEC)). We show that MaxEnTES is a reliable algorithm in terms of its higher output Signal-to-Noise Ratio and the negligibility of systematic errors that bias the estimated temperature in other TES procedures.
SEARCHING FOR NARROW EMISSION LINES IN X-RAY SPECTRA: COMPUTATION AND METHODS Taeyoung Park,1
van Dyk, David
SEARCHING FOR NARROW EMISSION LINES IN X-RAY SPECTRA: COMPUTATION AND METHODS Taeyoung Park,1 David of the high-redshift quasar PG 1634+706. Subject headinggs: methods: statistical -- quasars: emission lines 1 The detection and quantification of narrow emission lines in X-ray spectra is a challenging statistical task
Modelling the variability of the Fe K alpha line in accreting black holes
P. T. Zycki
The variability of the Fe K alpha line near 6.5 keV seems to be reduced compared to the variability of the hard X-rays which presumably drive the line emission. This is observed both in active galactic nuclei and galactic black hole binaries. We point out that such reduced variability, as well as lack of coherence between the variations of the line and the continuum, are a natural prediction of a propagation model of variability in the geometry of inner hot accretion flow. We compute detail model predictions of the variability characteristics which could be compared with current and future data. We also point out that the model requires a gradual disappearance of the cold disc, rather than a sharp transition from the cold disc to a hot flow.
Orbits and emission spectra from the 2014 Camelopardalids
NASA Astrophysics Data System (ADS)
Madiedo, Jos� M.; Trigo-Rodr�guez, Josep M.; Zamorano, Jaime; Izquierdo, Jaime; de Miguel, Alejandro S�nchez; Oca�a, Francisco; Ortiz, Jos� L.; Espartero, Francisco; Morillas, Lorenzo G.; Carde�osa, David; Moreno-Ib��ez, Manuel; Urz�iz, Marta
We have analysed the meteor activity associated with meteoroids of fresh dust trails of Comet 209P/LINEAR, which produced an outburst of the Camelopardalid meteor shower (IAU code #451, CAM) in 2014 May. With this aim, we have employed an array of high-sensitivity CCD video devices and spectrographs deployed at 10 meteor observing stations in Spain in the framework of the Spanish Meteor Network. Additional meteoroid flux data were obtained by means of two forward-scatter radio systems. The observed peak zenithal hourly rate was much lower than expected, of around 20 meteors h-1. Despite of the small meteor flux in the optical range, we have obtained precise atmospheric trajectory, radiant and orbital information for 11 meteor and fireball events associated with this stream. The ablation behaviour and low tensile strength calculated for these particles reveal that Camelopardalid meteoroids are very fragile, mostly pristine aggregates with strength similar to that of the Orionids and the Leonids. The mineral grains seem to be glued together by a volatile phase. We also present and discuss two unique emission spectra produced by two Camelopardalid bright meteors. These suggest a non-chondritic nature for these particles, which exhibit Fe depletion in their composition.
Low energy particle composition. [energy spectra, particle emission - solar flares
NASA Technical Reports Server (NTRS)
Gloeckler, G.
The energy spectra and composition of the steady or 'quiet-time' particle flux, whose origin is unknown was studied. Particles and photons which are associated with solar flares or active regions on the sun were also studied. Various detection techniques used to measure the composition and energy spectra of low energy particles are discussed. Graphs of elemental abundance and energy spectra are given.
Investigation of the spectra of phosphorescent organic light-emitting devices in relation to emission zone
Zhaoxin Wu; Liduo Wang; Gangtie Lei; Yong Qiu
The dependence of the electroluminescent spectra on the emission zone of blue electrophosphorscent light emitting diodes (PHOLEDs) was investigated. The light emission of a PHOLED was tuned from blue to greenish blue by adjusting the position of the emission zone in the PHOLED. Experimental results agreed well with the numerical simulation based on the effect of the wide-angle optical interference
Electronic Structure and Valence Band Spectra of Bi4Ti3O12
A. V. Postnikov; St. Bartkowski; F. Mersch; M. Neumann; E. Z. Kurmaev; V. M. Cherkashenko; S. N. Nemnonov; V. R. Galakhov
The x-ray photoelectron valence band spectrum and x-ray emission valence-band spectra (Ti K _beta_5, Ti L_alpha, O K_alpha) of Bi4Ti3O12 are presented (analyzed in the common energy scale) and interpreted on the basis of a band-structure calculation for an idealized I4\\/mmm structure of this material.
Relativistic Iron Line Emission from the Neutron Star Low-mass X-ray Binary 4U 1636-536
Dirk Pandel; Philip Kaaret; Stephane Corbel
We present an analysis of XMM-Newton and RXTE data from three observations of the neutron star LMXB 4U 1636-536. The X-ray spectra show clear evidence of a broad, asymmetric iron emission line extending over the energy range 4-9 keV. The line profile is consistent with relativistically broadened Fe K-alpha emission from the inner accretion disk. The Fe K-alpha line in 4U 1636-536 is considerably broader than the asymmetric iron lines recently found in other neutron star LMXBs, which indicates a high disk inclination. We find evidence that the broad iron line feature is a combination of several K-alpha lines from iron in different ionization states.
``Drifting tadpoles'' in wavelet spectra of decimetric radio emission of fiber bursts
H. M�sz�rosov�; M. Karlick�; J. Ryb�k; K. Jiricka
Aims: The solar decimetric radio emission of fiber bursts was investigated searching for the ``drifting tadpole'' structures proposed by theoretical studies. Methods: Characteristic periods with the tadpole pattern were searched for in the radio flux time series by wavelet analysis methods. Results: For the first time, we have found drifting tadpoles in the wavelet spectra of the decimetric radio emission
Calculation of spontaneous emission and gain spectra for quantum cascade lasers
Q. K. Yang; A. Z. Li
In this paper, a quantum cascade laser has been treated as a three-level system, and the calculation of the spontaneous emission and gain spectra has been given. In the calculation, the conduction band nonparabolicity and the injection and exit of electrons have been considered. Results have shown that with increasing injection current, the spontaneous emission peak blue shifts, and the
Analysis of emission spectra of Ho3+:LFBCd glasses
NASA Astrophysics Data System (ADS)
Naresh, V.; Buddhudu, S.
In the present paper, we report on the absorption and emission properties of (0.1-1.5 mol %) Ho3+ doped LFBCd (Li2O-LiF-B2O3-CdO) glasses prepared via melt quenching method. On exciting these glasses at (?exci) = 452 nm, two emissions at 556 nm (5S2?5I8; Green), 655 nm (5F5?5I8; Red) have been obtained. Upon exciting these glasses with a 980 nm diode laser, NIR emissions at 1195 nm (5I6?5I8), 1951 nm (5I7?5I8) have been measured for 1 mol % Ho3+:LFBCd glass. For higher concentration beyond 1.0 mol %, emission quenching of Ho3+ glass has been noticed and which has successfully been explained in terms of an energy level diagram. From absorption cross-section data, stimulated emission cross-section has been evaluated by applying McCumber's theory and further cross-sectional gain has also been computed for the emissions at 1195 nm (�1.20 ?m) and 1951 nm (�2.0 ?m) of 1 mol % Ho3+:LFBCd glass.
Laboratory technique for the measurement of thermal-emission spectra of greenhouse gases: CFC-12
NASA Astrophysics Data System (ADS)
Evans, W. F. J.; Puckrin, E.
A new technique has been developed to make possible the laboratory study of the infrared-emission spectra of gases of atmospheric interest. The thermal-emission spectra are in local thermodynamic equilibrium, just as they are in the atmosphere, and are not chemiluminescent. Demonstration results obtained by the use of this new technique are presented for dichlorodifluoromethane (CFC-12) at a pressure of 0.5 Torr in a cell with a path length of 5 cm. The measured cell spectra have been compared with simulations with the fascd3p radiation code. The measurements of the emission spectra of radiatively active gases may be important for the atmospheric greenhouse effect and global warming.
[A new automated method to identify emission line star from massive spectra].
Pan, Jing-Chang; Zhang, Cai-Ming; Wei, Peng; Luo, A-Li; Zhao, Yong-Heng
Stellar spectra are characterized by obvious absorption lines or absorption bands, while those with emission lines are usually special stars such as cataclysmic variable stars (CVs), HerbigAe/Be etc. The further study of this kind of spectra is meaningful. The present paper proposed a new method to identify emission line stars (ELS) spectra automatically. After the continuum normalization is done for the original spectral flux, line detection is made by comparing the normalized flux with the mean and standard deviation of the flux in its neighbor region The results of the experiment on massive spectra from SDSS DR8 indicate that the method can identify ELS spectra completely and accurately. Since no complex transformation and computation are involved in this method, the identifying process is fast and it is ideal for the ELS detection in large sky survey projects like LAMOST and SDSS. PMID:22870668
Calculation of gain and luminescence spectra of quantum-cascade laser structures taking into account asymmetric emission line broadening
Ushakov, D V; Manak, I S [Belarusian State University, Minsk (Belarus); Kononenko, V K [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus)
The energy levels, wave functions, and matrix elements of optical dipole transitions are calculated numerically for superlattice quantum-cascade structures. The effect of spectral broadening on the shape of emission spectra is estimated and semiphenomenological asymmetric profiles of emission line broadening are proposed. It is shown that the electroluminescence spectra well agree with the calculated spontaneous recombination spectra. (lasers)
Modeling the Infrared Emission Spectra of Specific PAH Molecules in Interstellar Space
NASA Astrophysics Data System (ADS)
Li, Aigen
The 3.3, 6.2, 7.7, 8.6 and 11.3 micron emission features ubiquitously seen in a wide variety of Galactic and extragalactic objects, are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. Although the PAH hypothesis is quite successful in explaining the general pattern of the observed emission spectra, so far there is no actual precise identification of a single specific PAH molecule in interstellar space. Therefore, when modeling the observed PAH emission spectra, astronomers usually take an empirical approach by constructing 'astro-PAHs' which do not represent any specific material, but approximate the actual absorption properties of the PAH mixture in astrophysical regions. We propose a Spitzer Theory Program to study the photoexcitation of specific PAH molecules and their ions in interstellar space, taking a statistical-mechanical (instead of thermal) approach. For most of the specific PAH molecules selected for this research (with a small number of vibrational degrees of freedom), thermal approximation is not valid. Using available laboratory and quantum-chemical data (e.g. vibrational frequencies, UV/visible/IR absorption cross sections), we will calculate the emission spectra of 21 representative specific PAH molecules and their ions, ranging from naphthalene to circumcoronene, illuminated by interstellar radiation fields of a wide range of intensities. This program will create a web-based 'library' of the emission spectra of 21 specific PAH molecules and their ions as a function of starlight intensities. This 'library' will be made publicly available by October 2008 on the internet at http://www.missouri.edu/~lia/. By comparing observed PAH spectra with model spectra produced by co-adding the emission spectra of different PAH molecules available in this 'library' (with different weights for different species), one will be able to estimate the total PAH mass and relative abundances of each PAH species, using real PAH properties.
Time-Resolved Emission Spectra Of Tryptophan And Proteins From Frequency-Domain Fluorescence Spectroscopy
NASA Astrophysics Data System (ADS)
Szmacineki, Henryk; Lakowicz, Joseph R.; Johnson, Michael L.
We report measurements of time-resolved emission spectra of N-acetyl-L-tryptophanamide (NATA), adrenocorticotropic hormone (ACTH, residues 1-24), and of S. Nuclease. These spectra were calculated from the frequency-response of the emission, measured at several wavelengths across the emission spectra. Measurements were performed on samples not quenched and quenched by acrylamide, the latter providing additional information on the short time events. The time-resolved center-of-gravity does not decay as a single exponential. At least two spectral relaxation times are needed to account for the present data. NATA and ACTH each display relaxation times near 50 and 800 ps, which may be characteristic of exposed tryptophan residues. S. nuclease displayed slower relaxation times near 0.5 and 10 ns, which probably reflect the dynamic protein matrix which surrounds the residue.
The oxygen emission lines in Wolf-Rayet spectra
NASA Technical Reports Server (NTRS)
Bhatia, A. K.; Underhill, Anne B.
The statistical equilibrium of oxygen in the line-emitting regions of WR stars is studied using the one-representative point theory of Castor and van Blerkom (1970) for a wider range of the radiation temperature, electron temperature, and electron density. Radiative processes, collisional processes, and electronic recombination are studied for a 59-level model atom. The level populations depart by large factors from those expected for LTE at the electron temperature and electron density. When the parameters have the values found previously by Bhatia and Underhill to be representative for WR stars, the oxygen atoms are strongly concentrated in the lower levels of O(2+), O(3+), and O(4+). The predicted relative energies in typical lines of O III, O IV, and O V for a solar abundance ratio of O to H are compatible with what is observed in WC and WN spectra.
Correction of phase anomalies of atmospheric emission spectra by the double-differencing method
NASA Astrophysics Data System (ADS)
Blom, Cornelis Eesge; Hopfner, Michael; Weddigen, Christian
Atmospheric emission measurements with the cryogenic airborne Michelson Interferometer for Passive Atmospheric Sounding revealed strongly disturbed phase and magnitude spectra. They were The phase information implied in the line structure of atmospheric spectra is used to specify a phase shift with respect to an instrumental phase spectrum, which was determined once from calibration measurements with the differencing method of Revercomb et al. [Appl. Opt. 27, 3210 (1988)].
A Fast NIR emission spectrometer for examining explosive events: emission spectra of PETN explosions containing silver and aluminum
NASA Astrophysics Data System (ADS)
Piecuch, Scott; Koch, Jon; Lightstone, Jim; Carney, Joel
A fast NIR spectrometer was constructed to make temporally and spectrally resolved emission measurements during post-detonation combustion of pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10% (by mass) Ag and Al microparticles. The post-detonation spectra are observed between 750 nm and 1500 nm at rates up to 46k-spectra/sec, and key features are identified. Immediately following break-out of the detonation, all measured spectra are highly structured due to atomic and molecular emission. This emission decays within the first 40 ?s following break-out and is found to have lifetimes similar to that of emission from various species collected in the visible (390-600 nm) by a time-resolved streak spectrometer. For the particle-doped charges, broadband NIR emission signals can be used to determine time-resolved gray-body temperatures of the particles. At early time (0-40 ?s after breakout) gray-body temperatures ranging from 3000 to 4500 K are measured, between 60 ?s and 300 ?s after breakout the particle temperature is found to cool significantly ranging from 1000 K to 1500 K. Complementary two-color pyrometry (800 and 1150 nm) temperature measurements are found to be in good agreement with early time data (0-25 ?s).
a Fast NIR Emission Spectrometer for Examining Explosive Events: Emission Spectra of Petn Explosions Containing Silver and Aluminum
NASA Astrophysics Data System (ADS)
Piecuch, S. R.; Koch, J. D.; Lightstone, J. M.; Carney, J. R.
A fast Near-Infrared (NIR) spectrometer was constructed to make temporally and spectrally resolved emission measurements during post-detonation combustion of pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10% (by mass) Ag and Al microparticles. The post-detonation spectra are observed between 750 nm and 1500 nm at rates up to 46,992-spectra/sec, and key features are identified. Immediately following break-out of the detonation, all measured spectra are highly structured due to atomic and molecular emission. This emission decays within the first 40 ?s following break-out and is found to have lifetimes similar to that of emission from various species collected in the visible (390-600 nm) by a time-resolved streak spectrometer. For the particle-doped charges, broadband NIR emission signals can be used to determine time-resolved gray-body temperatures of the particles. At early time (0-40 ?s after breakout) gray-body temperatures in the range of 3000 to 4500 K are measured, between 60 ?s and 350 ?s after breakout the particle temperature is found to cool significantly to the range of 1200 K to 1800 K. Complementary two-color pyrometry (800 and 1150 nm) temperature measurements are found to be in fair agreement with early time data (0-25 ?s).
Critical assessment of the emission spectra of various photosystem II core complexes.
Chen, Jinhai; Kell, Adam; Acharya, Khem; Kupitz, Christopher; Fromme, Petra; Jankowiak, Ryszard
We evaluate low-temperature (low-T) emission spectra of photosystem II core complexes (PSII-cc) previously reported in the literature, which are compared with emission spectra of PSII-cc obtained in this work from spinach and for dissolved PSII crystals from Thermosynechococcus (T.) elongatus. This new spectral dataset is used to interpret data published on membrane PSII (PSII-m) fragments from spinach and Chlamydomonas reinhardtii, as well as PSII-cc from T. vulcanus and intentionally damaged PSII-cc from spinach. This study offers new insight into the assignment of emission spectra reported on PSII-cc from different organisms. Previously reported spectra are also compared with data obtained at different saturation levels of the lowest energy state(s) of spinach and T. elongatus PSII-cc via hole burning in order to provide more insight into emission from bleached and/or photodamaged complexes. We show that typical low-T emission spectra of PSII-cc (with closed RCs), in addition to the 695�nm fluorescence band assigned to the intact CP47 complex (Reppert et al. J Phys Chem B 114:11884-11898, 2010), can be contributed to by several emission bands, depending on sample quality. Possible contributions include (i) a band near 690-691�nm that is largely reversible upon temperature annealing, proving that the band originates from CP47 with a bleached low-energy state near 693�nm (Neupane et al. J Am Chem Soc 132:4214-4229, 2010; Reppert et al. J Phys Chem B 114:11884-11898, 2010); (ii) CP43 emission at 683.3�nm (not at 685�nm, i.e., the F685 band, as reported in the literature) (Dang et al. J Phys Chem B 112:9921-9933, 2008; Reppert et al. J Phys Chem B 112:9934-9947, 2008); (iii) trap emission from destabilized CP47 complexes near 691�nm (FT1) and 685�nm (FT2) (Neupane et al. J Am Chem Soc 132:4214-4229, 2010); and (iv) emission from the RC pigments near 686-687�nm. We suggest that recently reported emission of single PSII-cc complexes from T. elongatus may not represent intact complexes, while those obtained for T. elongatus presented in this work most likely represent intact PSII-cc, since they are nearly indistinguishable from emission spectra obtained for various PSII-m fragments. PMID:25832780
Solvent Effect on the Absorption and Fluorescence Emission Spectra of Some Purine Derivatives: Spectrofluorometric Quantitative Studies
Hassan H. Hammud; Kamal H. Bouhadir; Mamdouh S. Masoud; Amer M. Ghannoum; Sulaf A. Assi
The absorption and emission spectra of six purine derivatives: adenine (I), N(9)-hydroxyethyladenine (II), N(6)-acetyladenine (III), N(6)-isobutyryladenine (IV), guanine (V), and N(2),N(9)-diacetylguanine (VI) have been investigated. The effects of solvent and pH on the positions of ?\\u000a max? (absorption) and ?\\u000a max? (emission) of these compounds were determined. Correlations between the absorption wavelength (?\\u000a max?) of these organic compounds and the
Soft X-ray emission spectra and electronic structure of some copper-beryllium alloys
A. I. Kozlenkov; A. I. Shulgin; A. V. Postnikov; A. I. Ivanovskii; V. A. Gubanov
The method of ultrasoft X-ray grating spectroscopy with electron microprobe excitation was used to obtain the Be K emission spectra of pure Be and some Cu-Be alloys. The experimental results are compared with those of electronic structure calculations performed in the cluster approximation. The two-peaked structure of the Be K emission band in alloys is due to the interaction between
NSDL National Science Digital Library
The Exploratorium
Learners construct a spectroscope out of a shoe box or mailing tube, diffraction grating, and other simple materials. They then use their spectroscope to observe spectra, the colors that make up light. Learners compare the spectra of various light sources. Use this activity to introduce learners to basic principles of light and color. Also, look at a related page about auroras to understand how distinguishing spectra of different atoms helps scientists understand the universe.
Emission spectra of selected SSME elements and materials
NASA Technical Reports Server (NTRS)
Tejwani, Gopal D.; Vandyke, David B.; Bircher, Felix E.; Gardner, Donald G.; Chenevert, Donald J.
Stennis Space Center (SSC) is pursuing the advancement of experimental techniques and theoretical developments in the field of plume spectroscopy for application to rocket development testing programs and engine health monitoring. Exhaust plume spectral data for the Space Shuttle Main Engine (SSME) are routinely acquired. The usefulness of this data depends upon qualitative and quantitative interpretation of spectral features and their correlation with the engine performance. A knowledge of the emission spectral characteristics of effluent materials in the exhaust plume is essential. A study of SSME critical components and their materials identified 30 elements and 53 materials whose engine exhaust plume spectral might be required. The most important were evaluated using SSC's Diagnostic Testbed Facility Thruster (DTFT), a 1200-lbf, liquid oxygen/gaseous hydrogen rocket engine which very nearly replicates the temperature and pressure conditions of the SSME exhaust plume in the first Mach diamond. This report presents the spectral data for the 10 most important elements and 27 most important materials which are strongly to moderately emitting in the DTFT exhaust plume. The covered spectral range is 300 to 426 nm and the spectral resolution is 0.25 nm. Spectral line identification information is provided and line interference effects are considered.
Retrieval of stratospheric ozone profiles from MIPAS\\/ENVISAT limb emission spectra: a sensitivity study
N. Glatthor; T. von Clarmann; H. Fischer; B. Funke; S. Gil-L�pez; U. Grabowski; M. H�pfner; S. Kellmann; A. Linden; M. L�pez-Puertas; G. Mengistu Tsidu; M. Milz; T. Steck; G. P. Stiller; D.-Y. Wang
We report on the dependence of ozone volume mixing ratio profiles, retrieved from limb emission infrared spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as the treatment of the background continuum, cloud filtering, spectral regions used for analysis and a series of further more technical parameter choices. The purpose of this investigation is
A Safe and Interactive Method of Illuminating Discharge Tubes for Studying Emission Spectra
ERIC Educational Resources Information Center
Lu, Zhe
Discharge tubes are useful tools for teaching emission spectra and the discrete energy levels of the Bohr model. A new setup uses a plasma globe to illuminate the discharge tube and allows a higher degree of interactivity owing to the omission of a traditional, high-voltage power source. The decreased power consumption also reduces the heating of�
Discernment of lint trash in raw cottton using multivariate analysis of excitation-emission luminescence spectra
Technology Transfer Automated Retrieval System (TEKTRAN)
Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...
Spontaneous and Stimulated-Emission Spectra of CdSnP2
J. L. Shay; L. M. Schiavone; E. Buehler; J. H. Wernick
We report the band-edge photoluminescence spectra of CdSnP2 crystals lightly doped with Cu or Ag. The emission from CdSnP2:Cu is dominated by a broad band 0.13 eV below the band gap at 1.240 eV (2�K). The emission from CdSnP2:Ag is much stronger and is dominated by a narrow band-to-band emission with three impurity peaks at slightly longer wavelengths. At the
New insights on the fluorescent emission spectra of prodan and laurdan.
Vequi-Suplicy, C�ntia C; Coutinho, Kaline; Lamy, M Teresa
Prodan and Laurdan are fluorescent probes largely used in biological systems. They were synthetized to be sensitive to the environment polarity, and their fluorescent emission spectrum shifts around 120�nm, from cyclohexane to water. Although accepted that their emission spectrum is composed by two emission bands, the origin of these two bands is still a matter of discussion. Here we analyze the fluorescent spectra of Prodan and Laurdan in solvents of different polarities, both by decomposing the spectrum into two Gaussian bands and by computing the Decay Associated Spectra (DAS), the latter with time resolved fluorescence. Our data show that the intensity of the lower energy emission band of Prodan and Laurdan (attributed, in the literature, to the decay of a solvent relaxed state) is higher in cyclohexane than in water, showing a decrease as the polarity of the medium increases. Moreover, in all solvents studied here, the balance between the two emission bands is not dependent on the temperature, strongly suggesting two independent excited states. Both bands were found to display a red shift as the medium polarity increases. We propose here a new interpretation for the two emission bands of Prodan and Laurdan in homogeneous solvents: they would be related to the emission of two independent states, and not to a pair of non-relaxed and solvent relaxed states. PMID:25753230
The Thermal Emission and Albedo of Super-Earths with Flat Transmission Spectra
NASA Astrophysics Data System (ADS)
Morley, Caroline; Fortney, Jonathan J.; Marley, Mark
Vast resources have been dedicated to characterizing the handful of planets with radii between Earth's and Neptune's that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Here, we present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break these degeneracies and constrain the atmospheric composition.Of the ~five small planets studied to date, four have radii in the near-IR consistent with being constant in wavelength. This suggests either that these planets all have higher mean molecular weight atmospheres than expected for hydrogen-dominated bulk compositions, or that the atmospheres of small planets are consistently enshrouded in thick hazes and clouds. For the particularly well-studied planet GJ 1214b, the measurements made using HST/WFC3 can rule out atmospheres with high mean molecular weights, leaving clouds as the sole explanation for the flat transmission spectrum. We showed in Morley et al. 2013 that these clouds and hazes can be made of salts and sulfides, which condense in the upper atmosphere of a cool H-rich atmosphere like GJ 1214b, or made of photochemical hazes such as soots, which result from methane photodissociation and subsequent carbon chemistry. Here, we explore how clouds thick enough to obscure the transmission spectrum change both thermal emission spectra and albedo spectra. These observations are complementary to transmission spectra measurements. Thermal emission probes deeper layers of the atmosphere, potentially below the high haze layer obscuring the transmission spectra; albedo spectra probe reflected starlight largely from the cloud particles themselves. Crucially, these complementary observations of planets with flat transmission spectra may allow us to break the degeneracies between cloud materials, cloud height and longitude, and bulk composition of the atmosphere. We make predictions for the observability of known planets for current and future telescopes.
Package for Interactive Analysis of Line Emission (Analysis of UV-X-Ray High-Resolution Emission Spectra)
NASA Technical Reports Server (NTRS)
Hunter, Paul (Technical Monitor); Kashyap, Vinay
The Package for Interactive Analysis of Line Emission (PINTofALE) is a suite of IDL routines designed to carry out spectroscopic analysis of high-resolution X-ray spectra. The current version is 1.5, and will shortly be upgraded to v2. A detailed description of the package, together with detailed documentation, example walk-throughs, science threads, and downloadable tar files, are available on-line.
Fig. 2: a) Spectra of PW And in a maximum and a minimum of emission; b) Variation in
Complutense de Madrid, Universidad
Fig. 2: a) Spectra of PW And in a maximum and a minimum of emission; b) Variation in EW( H) during different epochs (1999, 2002). Fig. 1: a) Spectra of V368 Cep in a maximum and a minimum of emission; b the clue for understanding the magnetic activity in solar-like stars. In this section we show some results
High-resolution measurements, line identification, and spectral modeling of K[alpha] transitions in Fe XVIII-XXV
Beiersdorfer, P.; Phillips, T. (Lawrence Livermore National Lab., CA (United States)); Jacobs, V.L. (Naval Research Lab., Washington, DC (United States). Condensed Matter and Radiation Sciences Div.); Hill, K.W.; Bitter, M.; von Goeler, S. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kahn, S.M. (California Univ., Berkeley, CA (United States))
The iron K[alpha] emission spectrum covering the wavelength region from 1.840 to 1.940 [Angstrom] is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m[Angstrom]. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s[sup r]2p[sup s] configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K[alpha] emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10[sup 13] cm[sup [minus]3]), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.
High-resolution measurements, line identification, and spectral modeling of K{alpha} transitions in Fe XVIII-XXV
Beiersdorfer, P.; Phillips, T. [Lawrence Livermore National Lab., CA (United States); Jacobs, V.L. [Naval Research Lab., Washington, DC (United States). Condensed Matter and Radiation Sciences Div.; Hill, K.W.; Bitter, M.; von Goeler, S. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Kahn, S.M. [California Univ., Berkeley, CA (United States)
The iron K{alpha} emission spectrum covering the wavelength region from 1.840 to 1.940 {Angstrom} is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m{Angstrom}. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s{sup r}2p{sup s} configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K{alpha} emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10{sup 13} cm{sup {minus}3}), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.
Phonon-Sideband Structures in Absorption and Emission Spectra of Organic Molecule Oligomers (N=2--6)
NASA Astrophysics Data System (ADS)
Nagasaka, Shin-ichiro; Miyakawa, Miki; Usugi, Tatsunori; Takahashi, Yoshio
Phonon-sideband structures in absorption and emission spectra of oligomers are investigated using a theoretical model: A Frenkel exciton (or molecular excitation) moves among molecules of oligomers with the transfer energy J and interacts with on-site intramolecular vibrations with the Haung-Rhys factor s. The intramolecular vibrations in the oligomers are coupled to each other with the coupling energy D. It is revealed that the absorption and emission spectra depend greatly on whether J is negative or positive. For the positive J case, the emission band splits off from the absorption band. Effects due to the coupling D to the absorption and emission spectra are studied. The molecular number dependence of the oligomers (N=2--6) on the spectra is studied and the obtained emission spectra are discussed in connection with organic light-emitting substances.
Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
Katsuji Koyama; Yoshiaki Hyodo; Tatsuya Inui; Hiroshi Nakajima; Hironori Matsumoto; Takeshi Go Tsuru; Tadayuki Takahashi; Yoshitomo Maeda; Noriko Yamazaki; Hiroshi Murakami; Shigeo Yamauchi; Yohko Tsuboi; Atsushi Senda; Jun Kataoka; Hiromitsu Takahashi; Stephen S Holt; Gregory V Brown
We have observed the diffuse X-ray emission from the Galactic center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provide excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are FeI K alpha at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (FeXXV K alpha) and hydrogenic (FeXXVI Ly alpha) ions of iron. In addition, K alpha lines from neutral or low ionization nickel (NiI K alpha) and He-like nickel (NiXXVII K alpha), and FeI K beta, FeXXV K beta, FeXXVI Ly beta, FeXXV K gamma and FeXXVI Ly gamma are detected for the first time. The line center energies and widths of FeXXV K alpha and FeXXVI Ly alpha favor a collisional excitation (CE) plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of FeXXV K alpha / FeXXV K beta is similar to the ionization temperature determined from that of FeXXV K alpha /FeXXVI Ly alpha. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic,in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar.
[Experimental study on the size spectra and emission factor of ultrafine particle from coal combustion].
Sun, Zai; Yang, Wen-jun; Xie, Xiao-fang; Chen, Qiu-fang; Cai, Zhi-liang
The emission characteristics of ultrafine particles released from pulverized coal combustion were studied, the size spectra of ultrafine particles (5.6-560 nm) were measured with FMPS (fast mobility particle sizer) on a self-built aerosol experiment platform. Meanwhile, a particle dynamic evolution model was established to obtain the particle deposition rate and the emission rate through the optimized algorithm. Finally, the emission factor was calculated. The results showed that at the beginning of particle generation, the size spectra were polydisperse and complex, the initial size spectra was mainly composed of three modes including 10 nm, 30-40 nm and 100-200 nm. Among them, the number concentration of mode around 10 nm was higher than those of other modes, the size spectrum of around 100-200 nm was lognormal distributed, with a CMD (count median diameter) of around 16 nm. Then, as time went on, the total number concentration was decayed by exponential law, the CMD first increased and then tended to be stable gradually. The calculation results showed that the emission factor of particles from coal combustion under laboratory condition was (5.54 x 10(12) � 2.18 x 10(12)) unit x g(-1). PMID:25826918
X-ray emission spectra and valence band structure of the 3d transition metal oxides
V. R. Galakhov; S. M. Butorin; E. Z. Kurmaev; M. A. Korotin
X-ray emission oxygen Kalpha and 3d transition metal Lalpha spectra for MnO, FeO, CoO, NiO, and CuO have been compared in the same energy scale by using Me 2p and O 1s binding energies. In the valence band of CuO the so-called d-p resonance between Cu 3d and O 2p states was observed. The 3d metal Lalpha-spectra for these oxides
Emissivity and Reflectance Spectra of Asteroid Analogs: Their Dependence on Emerging Angle
NASA Astrophysics Data System (ADS)
Maturilli, A.; Helbert, J.; D'Amore, M.; Ferrari, S.
Very few laboratory experiments have been made up to date to understand the influence of emerging angle on measured emissivity spectra of particulate materials. Most of the existing works are based on measurements of flat, solid surfaces (mainly metals) that are not easily usable for the analysis of remote sensing data. We believe that a systematic study on the influence of emerging angle for emissivity and reflectance laboratory spectra of asteroids analogs is of crucial importance for the interpretation of data from future missions to asteroids (among them, NASA OSIRIS-Rex, and JAXA Hayabusa II) and for the modelling of surface properties of minor bodies in general. At the Planetary Emissivity Laboratory (PEL) of DLR in Berlin we set-up an experiment to measure the emissivity of two asteroid analogs, fine powdered (<25 ?m) meteorite Millbillillie and a synthetic enstatite at surface temperature of 373K, with emerging angle (e) from 0� to 60�, with 10� step intervals. Special wedges have been created to incline the samples at the right emission angles: to prevent powder to slipper from the sample cups (always happening for e>30�), the samples have been packed using ethanol. For comparisons, we measured reflectance spectra of the same samples, keeping the incidence angle to the allowed minimum (i=13�) and varying the emerging angle as we did for emissivity measurements. All the data show very small spectral variations up to e=30�, while starting from e=40� the changes in band depth and shape become significant, and increase for each 10� step of increasing emerging angle.
Secondary electron emission characteristics of C(111) and the observation of double-peaked emission spectra
NASA Astrophysics Data System (ADS)
Yater, J. E.; Shih, A.
Secondary electron emission spectroscopy (SEES) is used to investigate the low-energy electron emission characteristics of the C(111) surface. A negative electron affinity (NEA) is observed at hydrogenated and cesiated C(111) surfaces, and very high secondary electron yields are measured from these surfaces. The emission from both surfaces is sharply peaked at low energy, although the cesiated surface produces greater energy spread than the hydrogenated surface. Yield measurements are uniform across the hydrogenated and cesiated surfaces, but energy distribution curves (EDCs) contain emission features that depend on the measurement position on the surface. Specifically, an intense secondary emission peak centered above Ec is observed in EDCs measured at all positions while a weaker peak lying completely below Ec appears only at specific regions of the surface. The intense peak is well understood and has been observed in EDCs taken from NEA surfaces of C(100) and chemical vapor deposited diamond. However, the weaker peak has not been observed in previous SEES studies of diamond. This peak corresponds to electron emission from surface or defect electronic states in the energy gap, and it is manifested in the EDCs only when ? is sufficiently lowered by the adsorption of H or Cs. Although the origin of the surface or defect states is not known, it appears to be associated with structural properties of the C(111) surface.
Local H i Emissivity Measured with Fermi-LAT and Implications for Cosmic-Ray Spectra
NASA Astrophysics Data System (ADS)
Casandjian, Jean-Marc
Cosmic-ray (CR) electrons and nuclei interact with the Galactic interstellar gas and produce high-energy ?-rays. The ?-ray emission rate per hydrogen atom, called emissivity, provides a unique indirect probe of the CR flux. We present the measurement and the interpretation of the emissivity in the solar neighborhood for ?-ray energy from 50 MeV to 50 GeV. We analyzed a subset of 4 yr of observations from the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope (Fermi) restricted to absolute latitudes 10^\\circ \\lt | b| \\lt 70^\\circ . From a fit to the LAT data including atomic, molecular, and ionized hydrogen column density templates, as well as a dust optical depth map, we derived the emissivities, the molecular hydrogen�to�CO conversion factor {X}{CO}=(0.902+/- 0.007)� {10}20 cm?2 (K km s?1)?1, and the dust-to-gas ratio {X}{DUST}=(41.4+/- 0.3)� {10}20 cm?2 mag?1. Moreover, we detected for the first time ?-ray emission from ionized hydrogen. We compared the extracted emissivities to those calculated from ?-ray production cross sections and to CR spectra measured in the heliosphere. We observed that the experimental emissivities are reproduced only if the solar modulation is accounted for. This provides a direct detection of solar modulation observed previously through the anticorrelation between CR fluxes and solar activity. Finally, we fitted a parameterized spectral form to the heliospheric CR observations and to the Fermi-LAT emissivity and obtained compatible local interstellar spectra for proton and helium kinetic energy per nucleon between between 1 and 100 GeV and for electron�positrons between 0.1 and 100 GeV.
High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers
Park, H; Izumi, N; Key, M H; King, J A; Koch, J A; Landen, O L; Patel, P K; Price, D F; Remington, B A; Robey, H F; Snavely, R A; Tabak, M; Town, R J; Wickersham, J E; Stoeckl, C; Storm, M; Theobald, W; Chambers, D M; Eagelton, R; Goldsack, T; Clarke, R J; Heathcote, R; Giraldez, E; Nikroo, A; Steinman, D A; Stephens, R B; Zhang, B B
We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K{alpha} radiation. 1-D radiography experiments using small-edge-on foils resolved 10 {micro}m features with high contrast. We tested a variety of small volume 2-D point sources such as cones, wires, and embedded wires, measuring photon yields and comparing our measurements with predictions from hybrid-PIC LSP simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the 20-100 keV energy range. An initial look at some of these detector issues is also presented.
Emission Lines between 1 and 2 keV in Cometary X-Ray Spectra
NASA Astrophysics Data System (ADS)
Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J.
We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.
Influence of the projectile charge state on electron emission spectra from a Cu(111) surface
NASA Astrophysics Data System (ADS)
Archubi, C. D.; Silkin, V. M.; Gravielle, M. S.
Double differential electron emission distributions produced by grazing impact of fast dressed ions on a Cu(111) surface are investigated focusing on the effects of the electronic band structure. The process is described within the Band-Structure-Based approximation, which is a perturbative method that includes an accurate representation of the electron-surface interaction, incorporating information of the electronic band structure of the solid. Differences in the behavior of the emission spectra for He+ q, Li+ q, Be+ q and C+ q projectiles with different charge states q are explained by the combined effect of the projectile trajectory and the projectile charge distribution.
Measurements of trace constituents from atmospheric infrared emission and absorption spectra, a feasibility study
NASA Technical Reports Server (NTRS)
Goldman, A.; Williams, W. J.; Murcray, D. G.
The feasibility of detecting eight trace constituents (CH4, HCl, HF, HNO3, NH3, NO, NO2 and SO2) against the rest of the atmospheric background at various altitudes from infrared emission and absorption atmospheric spectra was studied. Line-by-line calculations and observational data were used to establish features that can be observed in the atmospheric spectrum due to each trace constituent. Model calculations were made for experimental conditions which approximately represent state of the art emission and absorption spectrometers.
Near infrared emission spectra of CoH and CoD Iouli E. Gordon a
Le Roy, Robert J.
Near infrared emission spectra of CoH and CoD Iouli E. Gordon a , Robert J. Le Roy b , Peter FH and CoD molecules have been recorded in the 640 nm to 3.5 lm region using a Fourier transform U4 electronic transition of CoD, and five bands for the corresponding transition of CoH. The (0
Comparison of explicit calculations for n =3--8 dielectronic satellites of the Fe XXV K. alpha. resonance line with experimental data from the tokamak fusion test reactor
Decaux, V.; Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Park, H. (Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)); Bhalla, C.P. (Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States))
Dielectronic satellite spectra of the Fe XXV {ital K}{alpha} resonance line observed from tokamak fusion test reactor plasmas have been compared with recent explicit calculations for the {ital n}=3--8 dielectronic satellites as well as the earlier theoretical predictions, which were based on the 1/{ital n}{sup 3} scaling law for {ital n}{gt}4 satellites. The analysis has been performed by least-squares fits of synthetic spectra to the experimental data. The synthetic spectra constructed from both theories are in good agreement with the observed data. However, the electron-temperature values obtained from the fit of the present explicit calculations are in better agreement with independent measurements.
The X-ray spectra and spectral variability of intermediate type Seyfert galaxies: ASCA observations of NGC 4388 and ESO 103-G35
Karl Forster; Karen M. Leighly; Laura E. Kay
The X-ray spectra of two intermediate type Seyfert galaxies are investigated using ASCA observations separated by more than a year. Both NGC 4388 and ESO 103-G35 exhibit strong, narrow Fe K alpha line emission and absorption by cold neutral gas with a column density ~ 10^23 cm^-2, characteristic of the X-ray spectra of type 2 Seyfert galaxies. The power law continuum flux has changed by a factor of 2 over a time-scale of ~ 2 years for both objects, declining in the case of NGC 4388 and rising in ESO 103-G35. No variation was observed in the equivalent width of the Fe K alpha line in the spectra of NGC 4388, implying that the line flux declined with the continuum. We find that the strength of the line cannot be accounted for by fluorescence in line-of-sight material with the measured column density unless a `leaky-absorber' model of the type favored for IRAS 04575-7537 is employed. The equivalent width of the Fe K alpha emission line is seen to decrease between the observations of ESO 103-G35 while the continuum flux increased. The 1996 observation of ESO 103-G35 can also be fitted with an absorption edge at 7.4 $\\pm$ 0.2 keV due to partially ionized iron, and when an ionized absorber model is fitted to the data it is found that the equivalent column of neutral hydrogen rises to 3.5 x 10^23 cm^-2. The Fe K alpha line flux can be accounted by fluorescence in this material alone and this model is also a good representation of the 1988 and 1991 Ginga observations. There is then no requirement for a reflection component in the ASCA spectra of ESO 103-G35 or NGC 4388.
TDDFT prediction of UV-vis absorption and emission spectra of tocopherols in different media.
Bakhouche, Kahina; Dhaouadi, Zoubeida; Lahmar, Souad; Hammout�ne, Dalila
We use the TDDFT/PBE0/6-31+G* method to determine the electronic absorption and emission energies, in different media, of the four forms of tocopherol, which differ by the number and the position of methyl groups on the chromanol. Geometries of the ground state S0 and the first singlet excited state S1 were optimized in the gas phase, and various solvents. The solvent effect is evaluated using an implicit solvation model (IEF-PCM). Our results are compared to the experimental ones obtained for the vitamin E content in several vegetable oils. For all forms of tocopherols, the HOMO-LUMO first vertical excitation is a ?-?* transition. Gas phase and non-polar solvents (benzene and toluene) give higher absorption wavelengths than polar solvents (acetone, ethanol, methanol, DMSO, and water); this can be interpreted by a coplanarity between the O-H group and the chroman, allowing a better electronic resonance of the oxygen lone pairs and the aromatic ring, and therefore giving an important absorption wavelength, whereas the polar solvents give high emission wavelengths comparatively to gas phase and non-polar solvents. Fluorescence spectra permit the determination, the separation, and the identification of the four forms of tocopherols by a large difference in emission wavelength values. Graphical Abstract Scheme from process methodological to obtain the absorption and emission spectra for tocopherols. PMID:26026299
Effects of heavy p doping on the polarized emission spectra and low-temperature luminescence spectra of GaAs\\/GaAsP strained-layer structures
A. V. Subashiev; Yu. A. Mamaev; B. D. Oskotskii; Yu. P. Yashin; V. K. Kalevich
The optical orientation of electron spins in heavily doped, strained GaAs\\/GaAsP layers with a deformation-split valence band\\u000a is studied experimentally. The observed polarized luminescence spectra and polarized photoemission (electron emission) spectra\\u000a are shown to be described well by a model which allows for smearing of the edges of the bands by the fluctuation potential\\u000a due to impurities, degeneracy of the
Mid-infrared spectra of PAH emission in Herbig AeBe stars
G. C. Sloan; L. D. Keller; W. J. Forrest; E. Leibensperger; B. Sargent; A. Li; J. Najita; D. M. Watson; B. R. Brandl; C. H. Chen; J. D. Green; F. Markwick-Kemper; T. L. Herter; P. D'Alessio; P. W. Morris; D. J. Barry; P. Hall; P. C. Myers; J. R. Houck
We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS). on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 um emission feature shifted to 6.3 um and the strongest C-C skeletal-mode feature occuring at 7.9 um instead of at 7.7 um as is often seen. Remarkably, none of the four stars have silicate emission. The strength of the 7.9 um feature varies with respect to the 11.3 um feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 um. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 um which may be related to the 12.7 um PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 um region, with the peak emission to the red of 8.0 um and no 8.6 um PAH feature.
Detection and Characterisation of H-{alpha} Emission Lines from Gaia BP/RP Spectra
Jaenes, Juergen [University of Tartu, Institute of Computer Science, Tartu Observatory (Estonia); Laur, Sven [University of Tartu, Institute of Computer Science (Estonia); Kolka, Indrek [Tartu Observatory (Estonia)
The Gaia probe, set to launch in 2011, will measure an estimated billion astronomical objects, producing an enormous amount of data. One of the data analysis tasks will be the identification and classification of measured objects. A vast majority of them will be 'ordinary' stars from our Galaxy but a certain percentage will belong to 'peculiar' objects. We are interested in detecting emission line stars (ELS). The characteristic feature of most ELS is the presence of a H-{alpha} emission line in their spectra. In the case of Gaia measurements, the influence of this line could be detected in low resolution prismatic spectra which will be recorded both in blue (BP) and red (RP) spectral region. In this work, we compare different algorithms for detecting and characterising H-{alpha} lines in Gaia spectra. These include a simple, integrated flux ratio-based algorithm and several machine learning algorithms, such as neural networks, support vector machines and support vector regression. We study line detection both from single-transit and over-sampled end-of-mission data.
TIR Emissivity Spectra of Thermally Processed Sulfates, Carbonates and Phyllosilicates as Analog Materials for Asteroid Surfaces
NASA Astrophysics Data System (ADS)
Maturilli, A.; Helbert, J.; D'Amore, M.; Ferrari, S.
At the Planetary Emissivity Laboratory (PEL) of the German Aerospace Center (DLR) in Berlin we are building a database of spectral measurements of several meteorites and other analogs for asteroid surfaces. Bi-directional reflectance of samples in the 1 to 100 ?m spectral range, are measured by using an evacuated (10-4 bar) Bruker Vertex 80V FTIR spectrometer and a Bruker A513 reflection unit, allowing phase angles between 26� and 170�. Emissivity in the 1 to 100 ?m spectral range is measured with the same instrument coupled with an external emissivity chamber, for sample temperatures ranging from low (50� C) to very high (above 800� C). We present here new measurements on sulfates, carbonates, and phyllosilicates in various grain size ranges. The setup was configured to simulate the thermal history of surface minerals on the asteroid 2008 EV5 during its revolution around the Sun. This asteroid is the scientific target of the ESA Marco Polo-R mission. The samples in vacuum (< 0.8 mbar) are measured at surface temperature around 70� C, then the same samples are heated to 220� C, and maintained at this temperature for one hour. Slowly the sample temperature is reduced back again to 70� C and a second measurement is taken. Emissivity spectra before and after thermal processing of the samples are complemented with reflectance measurements on samples fresh and after thermal processing. This comparison show us that for some minerals no spectral/structural changes appear, while others show signs of dehydration and among them some species show structural changes. We conclude that a proper spectral library of emissivity spectra for asteroid analogue materials must include thermally processed samples, reproducing the thermal evolution for the asteroid that is target of the actual investigation.
Searching for Narrow Emission Lines in X-ray Spectra: Computation and Methods
Taeyoung Park; David A. van Dyk; Aneta Siemiginowska
The detection and quantification of narrow emission lines in X-ray spectra is a challenging statistical task. The Poisson nature of the photon counts leads to local random fluctuations in the observed spectrum that often results in excess emission in a narrow band of energy resembling a weak narrow line. From a formal statistical perspective, this leads to a (sometimes highly) multimodal likelihood. Many standard statistical procedures are based on (asymptotic) Gaussian approximations to the likelihood and simply cannot be used in such settings. Bayesian methods offer a more direct paradigm for accounting for such complicated likelihood functions but even here multimodal likelihoods pose significant computational challenges. The new Markov chain Monte Carlo (MCMC) methods developed in 2008 by van Dyk and Park, however, are able to fully explore the complex posterior distribution of the location of a narrow line, and thus provide valid statistical inference. Even with these computational tools, standard statistical quantities such as means and standard deviations cannot adequately summarize inference and standard testing procedures cannot be used to test for emission lines. In this paper, we use new efficient MCMC algorithms to fit the location of narrow emission lines, we develop new statistical strategies for summarizing highly multimodal distributions and quantifying valid statistical inference, and we extend the method of posterior predictive p-values proposed by Protassov et al. (2002) to test for the presence of narrow emission lines in X-ray spectra. We illustrate and validate our methods using simulation studies and apply them to the Chandra observations of the high redshift quasar PG1634+706.
Excitation and emission spectra of rubidium in rare-gas thin-films.
Gerhardt, Ilja; Sin, Kyungseob; Momose, Takamasa
To understand the optical properties of atoms in solid state matrices, the absorption, excitation, and emission spectra of rubidium doped thin-films of argon, krypton, and xenon were investigated in detail. A two-dimensional spectral analysis extends earlier reports on the excitation and emission properties of rubidium in rare-gas hosts. We found that the doped crystals of krypton and xenon exhibit a simple absorption-emission relation, whereas rubidium in argon showed more complicated spectral structures. Our sample preparation employed in the present work yielded different results for the Ar crystal, but our peak positions were consistent with the prediction based on the linear extrapolation of Xe and Kr data. We also observed a bleaching behavior in rubidium excitation spectra, which suggests a population transfer from one to another spectral feature due to hole-burning. The observed optical response implies that rubidium in rare-gas thin-films is detectable with extremely high sensitivity, possibly down to a single atom level, in low concentration samples. PMID:22779665
A New Interpretation for the Variation in Starburst Galaxy Emission Line Spectra
NASA Astrophysics Data System (ADS)
Richardson, Chris T.; Allen, James T.; Baldwin, Jack A.; Hewett, Paul C.; Ferland, Gary J.; Meskhidze, Helen
Starburst galaxies have been easily distinguished from AGN using diagnostic emission line ratio diagrams constraining their excitation mechanism. Previous modeling of the star forming (SF) galaxy sequence outlined on the BPT diagram has led to the interpretation that high metallicity SF galaxies and low ionization SF galaxies are synonymous. Here, we present a new interpretation. Using a large sample of low-z SDSS galaxies, we co-added similar spectra of pure star forming galaxies allowing many weaker emission lines to act as consistency checks on strong line diagnostics. For the first time, we applied a locally optimally-emitting cloud (LOC) model to understand the physical reason for the variation in starburst galaxy emission line spectra. We fit over twenty diagnostic diagrams constraining the excitation mechanism, SED, temperature, density, metallicity, and grain content, making this work far more constrained than previous studies. Our results indicate that low luminosity SF galaxies could simply have less concentrated regions of ionized gas compared to their high luminosity counterparts, but have similar metallicities, thus requiring reevaluation about underlying nature of star forming galaxies.
High Resolution Spectra of Jupiter's Decametric Emission using the Long Wavelength Array Station 1
NASA Astrophysics Data System (ADS)
Higgins, C. A.; Clarke, T.; Thieman, J.; Skarda, J.; Imai, M.; Imai, K.; Reyes, F. J.
The Long Wavelength Array Station 1 (LWA1) provides excellent spectral and temporal resolution of Jupiter's decametric radio emissions over the bandwidth of 10-40 MHz. Using the full Stokes capabilities of LWA1 we show high resolution data of many well-known decametric features in Jupiter's spectrum including nested-arc structure, modulation lanes, S-bursts, narrow band N-events, and S-N event interactions. These new data allow for the testing of emission mechanisms relating to emission geometry, source locations, propagation paths, and S-burst acceleration models. In particular, LWA1 data showing simultaneous modulation lanes in both polarizations for a Jupiter Io-C event suggest that both polarizations might be coming from the same hemisphere, contrary to the emission theory. The well-known S-bursts show very complex structures such as frequency drifting, source splitting, and combination. Initial calculations of S-burst frequency drift rates are similar to previous data but new measurements at higher frequencies will help understand the electron acceleration mechanism. Moreover, some S-bursts show interaction with N-events by either triggering or quenching the resonance set up in the source emission zone. The linearly polarized feeds on LWA1 instrument also show excellent Faraday fringes in the Jupiter observations. Further analyses are needed to understand these phenomena and other features of Jupiter's decametric spectrum. We show Jupiter spectra and highlight the new capabilities of the LWA1 telescope.
Emission spectra analysis of arc plasma for synthesis of carbon nanostructures in various magnetic conditions
NASA Astrophysics Data System (ADS)
Li, Jian; Kundrapu, Madhusudhan; Shashurin, Alexey; Keidar, Michael
Arc discharge supported by the erosion of anode materials is one of the most practical and efficient methods to synthesize various high-quality carbon nanostructures. By introducing a non-uniform magnetic field in arc plasmas, high-purity single-walled carbon nanotubes (SWCNT) and large-scale graphene flakes can be obtained in a single step. In this paper, ultraviolet-visible emission spectra of arc in different spots under various magnetic conditions are analyzed to provide an in situ investigation for transformation processes of evaporated species and growth of carbon nanostructures in arc. Based on the arc spectra of carbon diatomic Swan bands, vibrational temperature in arc is determined. The vibrational temperature in arc center was measured around 6950 K, which is in good agreement with our simulation results. Experimental and simulation results suggest that SWCNT are formed in the arc periphery region. Transmission electronic microscope and Raman spectroscope are also employed to characterize the properties of carbon nanostructures.
Emission spectra analysis of arc plasma for synthesis of carbon nanostructures in various magnetic conditions
Li Jian; Kundrapu, Madhusudhan; Shashurin, Alexey; Keidar, Michael [Department of Mechanical and Aerospace Engineering, George Washington University, Washington, DC 20052 (United States)
Arc discharge supported by the erosion of anode materials is one of the most practical and efficient methods to synthesize various high-quality carbon nanostructures. By introducing a non-uniform magnetic field in arc plasmas, high-purity single-walled carbon nanotubes (SWCNT) and large-scale graphene flakes can be obtained in a single step. In this paper, ultraviolet-visible emission spectra of arc in different spots under various magnetic conditions are analyzed to provide an in situ investigation for transformation processes of evaporated species and growth of carbon nanostructures in arc. Based on the arc spectra of carbon diatomic Swan bands, vibrational temperature in arc is determined. The vibrational temperature in arc center was measured around 6950 K, which is in good agreement with our simulation results. Experimental and simulation results suggest that SWCNT are formed in the arc periphery region. Transmission electronic microscope and Raman spectroscope are also employed to characterize the properties of carbon nanostructures.
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study
NASA Astrophysics Data System (ADS)
Glatthor, N.; von Clarmann, T.; Fischer, H.; Funke, B.; Gil-L�pez, S.; Grabowski, U.; H�pfner, M.; Kellmann, S.; Linden, A.; L�pez-Puertas, M.; Mengistu Tsidu, G.; Milz, M.; Steck, T.; Stiller, G. P.; Wang, D.-Y.
We report on the dependence of ozone volume mixing ratio profiles, retrieved from limb emission infrared spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as the treatment of the background continuum, cloud filtering, spectral regions used for analysis and a series of further more technical parameter choices. The purpose of this investigation is to better understand the error sources of the ozone retrieval, to optimize the current retrieval setup and to document changes in the data versions. It was shown that the cloud clearing technique used so far (cloud index 1.8) does not reliably exclude all cloud-contaminated spectra from analysis. Through analysis of spectra calculated for cloudy atmospheres we found that the cloud index should be increased to a value of 3.0 or higher. Further, it was found that assignment of a common background continuum to adjacent microwindows within 5 cm-1 is advantageous, because it sufficiently represents the continuum emission by aerosols, clouds and gases as reported in the literature, and is computationally more efficient. For ozone retrieval we use ozone lines from MIPAS band A (685-970 cm-1) and band AB (1020-1170 cm-1) as well. Therefore we checked ozone retrievals with lines from bands A or AB only for a systematic difference. Such a difference was indeed found and could, to a major part, be attributed to the spectroscopic data used in these two bands, and to a minor part to neglection of modelling of non-local thermodynamic (non-LTE) emissions. Another potential explanation, a bias in the radiance calibration of level-1B spectra of bands A and AB, could largely be ruled out by correlation analysis and inspection of broadband spectra. Further upgrades in the ozone retrieval consist of application of an all-zero a-priori profile and a weaker regularization. Finally, the ozone distribution obtained with the new retrieval setup (data versions V3o_O3_7) was compared to the data version used before (V2_O3_2). Differences are smaller than pm0.4 ppmv in the altitude region 15-50 km. Further, differences to ozone measured by the HALogen Occultation Experiment (HALOE) on the Upper Atmospheric Research Satellite (UARS) are partly reduced with the new MIPAS data version.
Collisional-Radiative modeling of plasma UV-VIS emission spectra
NASA Astrophysics Data System (ADS)
Taylor, Andrew; Hyde, Alexander; Kamieneski, Richard; Batishchev, Oleg
Numerical collisional-radiative (CR) models can theoretically derive the temperature and excited state population densities of interstellar and experimental plasmas. Non-invasive photoemission spectroscopy is an invaluable diagnostic technique to verify CR model predictions. He , Ar , and N2 plasmas are created in vacuum tube, and emission is collected from 5mtorr to 20torr gas pressures. Effects of pressure on spectrum and population densities will be shown. We will discuss the CR modeling of various conditions and compare these simulations to the collected spectra. Work is supported by US DoD/ AFOSR Grants FA9550-10-1-0498 and FA2386-12-1-3006.
Modeling biological fluorescence emission spectra using Lorentz line shapes and nonlinear optimization.
Nation, Paul D; Howard, A Q; Webb, Lincoln J
Using the Levenberg-Marquardt nonlinear optimization algorithm and a series of Lorentzian line shapes, the fluorescence emission spectra from BG (Bacillus globigii) bacteria can be accurately modeled. This method allows data from both laboratory and field sources to model the return signal from biological aerosols using a typical LIF (lidar induced fluorescence) system. The variables found through this procedure match individual fluorescence components within the biological material and therefore have a physically meaningful interpretation. The use of this method also removes the need to calculate phase angles needed in autoregressive all-pole models. PMID:17712385
Calcium Pyroxenes at Mercurian Surface Temperatures: Investigation of In-Situ Emissivity Spectra.
NASA Astrophysics Data System (ADS)
Ferrari, Sabrina; Maturilli, Alessandro; Helbert, J�rn; Rossi, Manuela; Nestola, Fabrizio; D'Amore, Mario; Hiesinger, Harald
Several observations point to the possibility that Ca-rich (and low-Fe) clinopyroxenes could be common constituent minerals of the surface of Mercury. The upcoming ESA-JAXA BepiColombo mission to Mercury will carry on board the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) that will provide surface emissivity spectra in the wavelength range from 7-14 ?m. This spectral range is very useful to identify the fine-scale structural properties of several silicates including pyroxenes. The extreme daily surface temperature range of Mercury (70 to 725 K) that significantly affects the spectral signature of minerals will make the interpretation of MERTIS observations challenging. It has been shown that spectra of clinopyroxenes with similar calcium content display a deepening of the main absorption bands, and a shift of the band minima toward higher wavelengths with increasing temperatures. Similar shifts can also be observed at constant temperature with increasing iron content in the M2 site. Therefore, the thermal expansion induced by the increasing temperature simulates the presence of a larger cation (e.g., iron vs. magnesium) within the mineral structure. Interestingly, each band shifts by a different amount, representing a marker for the real chemistry of the sample. A detailed study of the described mineral behavior is fundamental to localize those spectral bands sensitive to the daily temperature range of the Mercury surface. In combination with the temperature measurements obtained independently by the radiometer channel of MERTIS this will help to further constrain the mineralogical interpretation of the MERTIS spectral data. Here we present high-temperature (up to 750 K) laboratory emissivity spectra of several augitic pyroxenes with different calcium contents and very different magnesium to iron ratios. The spectra were derived from individual well-preserved natural crystals of several pyroxenes of less than 125 ?m in size, which approaches the presumable size of Mercurian regolith particles. The emissivity measurements of the heated samples under vacuum have been conducted using the Mercury simulation chamber at the Planetary Emissivity Laboratory (PEL) in Berlin.
Calibrated 0.1-cml-1 IR emission spectra from 80 degrees N
NASA Astrophysics Data System (ADS)
Olson, J. R.; van Allen, J.; Fogal, P. F.; Murcray, F. J.; Goldman, A.
Spectra from a 0.1-cm-1 resolution absolutely calibrated emission interferometer installed near Eureka, Northwest Territories, Canada (80 degrees N, 86 degrees W), at the Arctic Stratospheric Observatory are presented. The Michelson-type interferometer has a maximum path difference of 10 cm and uses a liquid-N2-cooled HgCdTe detector, which covers the spectral region from 650 to 1250 cm-1. Spectral intervals containing CO2, HNO 3, and ozone have been modeled with a line-by-line radiative-transfer code and column amounts retrieved for the latter two constituents. The instrument and initial measurements are described.
Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals
NASA Astrophysics Data System (ADS)
Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.
Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760 nm (r2 = 0.88, RMSE = 7.54 x 107). When perfect retrievals were assumed (0% noise), retrievals remained good in the low emission regions on either side of the peaks-- those associated with the H alpha line at 655 nm (r2 = 0.83, RMSE =8.87 x 107) and the far-NIR wavelengths recently utilized for satellite retrievals: a K line at 770 nm (r2 = 0.85, RMSE = 8.36 x 107) and the 750-770 nm interval (r2 = 0.88, RMSE = 6.92 x 107). However, the atmosphere and satellite observations are expected to add noise to retrievals. Adding 5% random error to these relationships did not seriously impair the retrieval successes in the red and far-red peaks (r2 ~ 0.85, RMSEs = 6.31 x 107). A greater impact occurred (reducing retrieval success by ~10%) when adding 5% noise for the far-NIR narrow band at 770 nm (r2 ~ 0.70, RMSE ~ 8.5 x 107). When a 10% random error was added, the retrieval successes fell to ~68 � 7% for all retrieval wavebands, and RMSEs increased by a factor of 10. This laboratory approach will be critical to calibrate space borne retrievals, but additional information across plant species is needed. Furthermore, this experiment indicates that ChlF retrievals from space should include information from the red and far-red peak emission regions, since the true total fluorescence signal is the desired parameter for Earth carbon and energy budgets.
Computation of AlO B2?+ ? X2?+ emission spectra.
Parigger, Christian G; Hornkohl, James O
Application of molecular spectroscopy to analytical chemistry usually requires accurate description of the particular transition of interest. In this communication we describe the creation of a list of spectral lines. Following the introduction and definition of the line strength, we present a recipe for computation of diatomic-line-strengths, including the H�nl-London factor and electric dipole line strength for each spectral line. The diatomic eigenfunction is discussed including Hund's case basis functions. In our data tables we prefer use of Hund's case (a) basis, and we apply the usual Born-Oppenheimer approximation for the electronic-vibrational strengths. This allows us to generate the table of line strengths that we frequently apply for spectroscopic temperature determination. Using these line-strength tables, we present theoretical AlO emission spectra for the B-X system of AlO. These emission spectra are computed for temperatures of 3000 and 6000 K and for typical spectroscopic resolution used in laser-induced optical breakdown studies. PMID:21798795
Correction of emission spectra in microspectrofluorimetry using a reference lamp: computations.
Galassi, L
Accurate correction of emission spectra in microspectrofluorimetry, using a reference lamp, may require that a factor for the emissivity of tungsten be introduced. This is only possible provided that the true temperature of the lamp filament is known. A method is given for obtaining the true temperature from the knowledge of the colour temperature. Also, the values of the spectral concentration of the radiance of the black body, either computed according to Planck's equation or taken from available published tables, have to be converted from energetic units to units of quanta since the photomultiplier is linear not to absorbed power but to units of quanta. When the fluorescence spectra to be corrected extend into the far red it is preferable to use a lower temperature (by lowering the supply voltage) than that for which the lamp is certified. It is possible to determine the new temperature (and then the corresponding spectral distribution) by taking a few pairs of measurements at different wavelengths both at the lower voltage and at the voltage for which the lamp is certified and then introducing these values in a non-linear regression soluble on a PC with a curve fitting program. The microscope tungsten halogen lamp can conveniently be used as a reference, thanks to its small size and its steady spectral characteristics. When high accuracy is required, however, the halogen lamp should be calibrated against a certified ribbon filament lamp. PMID:1380859
Ultrafast K-alpha Thomson scattering from shock compressed matter for use as a dense matter diagnostic
NASA Astrophysics Data System (ADS)
Kritcher, Andrea Lynn
Material conditions in the high-energy-density-physics regime relevant for the study of planetary formation, the modeling of planetary composition, and for inertial confinement fusion experiments, such as on the future National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), can be produced and studied in the laboratory using high powered lasers that shock compress material to pressures greater than > 1 Mbar. Measurement of the compression and heating of shock-compressed dense matter at high pressures is fundamental in the study and understanding of the physical and chemical properties of these extreme states. Investigation of the behavior of the ionic and elecronic properties in this regime is important to determine the equation of state and thermodynamic properties of materials under extreme conditions, that are not currently well understood. In previous work, x-ray Thomson scattering has been employed to characterize dense matter conditions, ne > 3 x 10 21cm-3, that cannot be probed using the well established technique of optical Thomson scattering. These experiments employed x-ray probes with a temporal resolution of 100 ps. However, for the full characterization of strong shocks in dense matter, an x-ray source that provides picosecond temporal resolution, i.e. K-alpha x-rays, is desirable. Presented in this thesis, are the first spectrally and temporally resolved x ray Thomson scattering measurements using ultrafast (10 ps) Ti K-alpha x-rays. These measurements have provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 nanosecond heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models, mainly dependent on choice of Equation of State (EOS). Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of three times solid density. The quality of data achieved in these experiments demonstrates the capability for single-shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets. In addition, presented in this thesis are the first ultrafast temporally, spectrally and angularly resolved x-ray Thomson scattering measurements from shock-compressed matter. These experiments allowed the testing of theoretical models used in the multi-shock experiments to infer temperatures, from dependency of the elastic scattering feature intensity on the ion form factor. The experimental spectra provided the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples were well characterized by inelastic Compton and Plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions. Also presented in this thesis are proof-of-principle x-ray scattering measurements from inertial confinement fusion implosion targets, and a discussion of ongoing and future work. These first measurements provided temperature and density conditions for imploding CH shells for the investigation of the capsule ablator adiabat. Measurement and understanding of the adiabat response to implosion and target conditions is important and must be kept low for optimum fuel compression and tar
Proton, electron and K-alpha emission from micro-scale copper cone targets
S. A. Gaillard; K. A. Flippo; D. C. Gautier; J. L. Kline; J. Workman; F. Archuleta; R. Gonzales; T. Hurry; R. Johnson; S. Letzring; D. Montgomery; S.-M. Reid; T. Shimada; Y. Sentoku; T. E. Cowan; J. Rassuchine; M. Lowenstern; E. Mucino
Summary form only given. Results from experiments performed at the recently commissioned LANL 200 TW Trident short-pulse laser at ~5??1019 W\\/cm2 (80-100 J and ~600 fs) are presented. We have conducted laser-ion acceleration experiments comparing flat foils and new Cu micro-cone targets in three separate geometries (flat-top, funnel, and snub-nose) to elucidate the production of hot electrons and ions in
Random mixtures of polycyclic aromatic hydrocarbon spectra match interstellar infrared emission
NASA Astrophysics Data System (ADS)
Rosenberg, Marissa J. F.; Bern�, Olivier; Boersma, Christiaan
The mid-infrared (mid-IR; 5-15 ?m) spectrum of a wide variety of astronomical objects exhibits a set of broad emission features at 6.2, 7.7, 8.6, 11.3, and 12.7 ?m. About 30 years ago it was proposed that these signatures are due to emission from a family of UV heated nanometer-sized carbonaceous molecules known as polycyclic aromatic hydrocarbons (PAHs), causing them to be referred to as aromatic IR bands (AIBs). Today, the acceptance of the PAH model is far from settled, as the identification of a single PAH in space has not yet been successful, and physically relevant theoretical models involving true PAH cross sections do not reproduce the AIBs in detail. In this paper, we use the NASA Ames PAH IR Spectroscopic Database, which contains over 500 quantum-computed spectra, in conjunction with a simple emission model, to show that the spectrum produced by any random mixture of at least 30 PAHs converges to the same kernel-spectrum. This kernel-spectrum captures the essence of the PAH emission spectrum and is highly correlated with observations of AIBs, strongly supporting PAHs as their source. Furthermore, the fact that a large number of molecules are required implies that spectroscopic signatures of the individual PAHs contributing to the AIBs spanning the visible, near-IR, and far-IR spectral regions are weak, explaining why they have not yet been detected. An improved effort, joining laboratory, theoretical, and observational studies of the PAH emission process, will support the use of PAH features as a probe of physical and chemical conditions in the near and distant Universe. Appendices are available in electronic form at http://www.aanda.org
Emissivity Spectra of Meteoritic Powders mixed with Liquid Formamide (NH2COH) at Different Temperatures
NASA Astrophysics Data System (ADS)
Raffaele, S.; Maturilli, A.; D'Amore, M.; Ferrari, S.; Helbert, J.
We set-up an experiment at the Planetary Emissivity Laboratory (PEL) to investigate a key aspect in the prebiotic chemistry of formamide: the surface reactivity of minerals used as catalysts. The interaction of formamide and the reaction products on mineral surface, as well as, the sequestration processes in the mineral pores, can facilitate the concentration of products allowing for possible polymerization. Three meteorites, NWA2828 (PEL ID 00000887), Al Haggounia (PEL ID 00000888), and Dhofar959 (PEL ID 00000889), were used in this experiment. All the samples were reduced in the grain size fraction < 125 ?m and stored in a desiccator before measuring. Each sample was poured in one from a set of identical stainless steel cups, having 5 mm thick bottom, internal diameter 50 mm, rim thickness 2 mm, and 20 mm total height. Emissivity of the samples was measured by means of a Bruker Vertex 80V coupled to an emissivity chamber (equipped with a rotating carousel to measure several samples without breaking the vacuum), both evacuable to < 1 mbar. The dry samples were placed in the emissivity chamber, each of them having a temperature sensor in contact with the surface of the sample, reading the effective temperature of the emitting skin. The 'dry' meteorites were measured in vacuum (0.8 mbar) at 70� C on the sample surface, successively liquid formamide was vaporized on the samples surface, the cup was immediately transferred in the emissivity chamber, and evacuated. Each sample was measured at 70�, 100�, 140�, and 200� C. Then each cup was cooled in vacuum and put back in the desiccator. For each sample after this thermal processing, a small amount of heated material was used to fill a cup for reflectance measurements. Since cold reflectance measurements cannot be compared with hot emissivity, those measurements have been taken to better understand the processes happening in the moisturized soil after heating. For all of the samples, when heating at 70�C we noticed in the emissivity spectra strong signatures attributable to liquid formamide. We interpret them as being originated from a column of hot vaporized formamide, lying above the sample surface. For all the samples this effect vanished already at 100�C, probably due to complete evaporation of liquid formamide that was deposited on the meteorite sample surfaces. However, all the spectra measured at 100� and 140� C show signs of the presence of formamide, that we infer from comparing them with the 70� C dry measurement of the same sample. For 2 samples out of 3, when heating at 200�C (and only there) a new feature appears at 7.08 ?m. This band is very close to a similar band that liquid formamide has at 7.19 ?m, and that was even present in all the spectra of wet meteorites taken at 70�C. We interpret this band shift as a possible sign of interaction of formamide with the catalyst (the meteorite powder): the CH bend responsible for that is probably strengthening.
Somatic mutations in PI3K[alpha]: Structural basis for enzyme activation and drug design
Gabelli, Sandra B.; Mandelker, Diana; Schmidt-Kittler, Oleg; Vogelstein, Bert; Amzel, L. Mario (JHU); (HHMI)
The PI3K pathway is a communication hub coordinating critical cell functions including cell survival, cell growth, proliferation, motility and metabolism. Because PI3K{alpha} harbors recurrent somatic mutations resulting in gains of function in human cancers, it has emerged as an important drug target for many types of solid tumors. Various PI3K isoforms are also being evaluated as potential therapeutic targets for inflammation, heart disease, and hematological malignancies. Structural biology is providing insights into the flexibility of the PI3Ks, and providing basis for understanding the effects of mutations, drug resistance and specificity.
Simulated infrared emission spectra of highly excited polyatomic molecules: a detailed model of the PAH-UIR hypothesis
NASA Technical Reports Server (NTRS)
Cook, D. J.; Saykally, R. J.
A detailed description of the polycyclic aromatic hydrocarbon (PAH)/unidentified infrared band (UIR) mechanism is presented in which experimental spectral bandshape functions are used to simulate IR emission spectra for individual molecules. These spectra are additively superimposed to produce a conglomerate spectrum representative of a family of PAH molecules. Ab initio vibrational frequencies and intensities for nine PAHs (neutral and cationic) as large as ovalene are used in conjunction with measured bandshape and temperature-dependent redshift data to simulate the UIR bands. The calculated spectra of cations provide a closer match to the UIRs than do those of the neutrals. However, the PAH cations used in the simulations fail to reproduce the details of the UIR emission spectra. The discrepancies are potentially alleviated if both larger PAHs and a greater number of PAHs were included in the simulation.
Spitzer-IRS spectra of disks around T Tauri stars II. PAH emission features
V. C. Geers; J. -C. Augereau; K. M. Pontoppidan; C. P. Dullemond; R. Visser; J. E. Kessler-Silacci; N. J. Evans II; E. F. van Dishoeck; G. A. Blake; A. C. A. Boogert; J. M. Brown; F. Lahuis; B. Merin
Aims: We search for PAH features towards T Tauri stars and compare them with surveys of Herbig Ae/Be stars. The presence and strength of the PAH features are interpreted with disk radiative transfer models exploring the PAH feature dependence on the incident UV radiation, PAH abundance and disk parameters. Methods: Spitzer Space Telescope 5-35 micron spectra of 54 pre-main sequence stars with disks were obtained, consisting of 38 T Tauri, 7 Herbig Ae/Be and 9 stars with unknown spectral type. Results: Compact PAH emission is detected towards at least 8 sources of which 5 are Herbig Ae/Be stars. The 11.2 micron PAH feature is detected in all of these sources, as is the 6.2 micron PAH feature where short wavelength data are available. However, the 7.7 and 8.6 micron features appear strongly in only 1 of these 4 sources. PAH emission is observed towards at least 3 T Tauri stars (8% detection rate). The lowest mass source with PAHs in our sample is T Cha (G8). All 4 sources in our sample with evidence for dust holes in their inner disk show PAH emission, increasing the feature/continuum ratio. Typical 11.2 micron line intensities are an order of magnitude lower than those observed for the more massive Herbig Ae/Be stars. Measured line fluxes indicate PAH abundances that are factors of 10-100 lower than standard interstellar values. Conversely, PAH features from disks exposed to stars with TeffPAH abundances. Disk modeling shows that the 6.2 and 11.2 micron features are the best PAH tracers for T Tauri stars, whereas the 7.7 and 8.6 micron bands have low feature over continuum ratios due to the strongly rising silicate emission.
Time resolved spectra in the infrared absorption and emission from shock heated hydrocarbons
NASA Astrophysics Data System (ADS)
Bauer, S. H.; Borchardt, D. B.
We have extended the wavelength range of our previously constructed multichannel, fast recording spectrometer to the mid-infrared. With the initial configuration, using a silicon-diode (photovoltaic) array, we recorded light intensities simultaneously at 20 adjacent wavelengths, each with 20 ?s time resolution. For studies in the infrared the silicon diodes are replaced by a 20 element PbSe (photoconducting) array of similar dimensions (1�4 mm/element), cooled by a three-stage thermoelectric device. These elements have useful sensitivities over 1.0-6.7 ?m. Three interchangeable gratings in a 1/4 m monochromator cover the following spectral ranges: 1.0-2.5 ?m (resolution 33.6 cm-1) 2.5-4.5 ?m (16.8 cm-1) 4.0-6.5 ?m (16.7 cm-1). Incorporated in the new housing there are individually controlled bias-power sources for each detector, two stages of analogue amplification and a 20-line parallel output to the previously constructed digitizer, and record/hold computer. The immediate application of this system is the study of emission and absorption spectra of shock heated hydrocarbons-C2H2, C4H4 and C6H6-which are possible precursors of species that generate infrared emissions in the interstellar medium. It has been recently proposed that these radiations are due to PAH that emit in the infrared upon relaxation from highly excited states. However, it is possible that such emissions could be due to shock-heated low molecular-weight hydrocarbons, which are known to be present in significant abundances, ejected into the interstellar medium during stellar outer atmospheric eruptions. The full Swan band system appeared in time-integrated emission spectra from shock heated C2H2 (1% in Ar; T5eq~=2500K) no soot was generated. At low resolution the profiles on the high frequency side of the black body maximum show no distinctive features. These could be fitted to Planck curves, with temperatures that declined with time from an initial high that was intermediate between T5 (no conversion) and T5 (eq).
Spectrophotometry of prominences in the phase preceding decay. [line spectra and spectral emission
NASA Technical Reports Server (NTRS)
Rakhubovskiy, A. S.
The results are presented of spectrophotometric processing of prominence spectra in both the quiet and the decay phases. A catalog was compiled of equivalent widths, central intensities, Doppler half-widths, and half-widths of emission lines. The reduced Doppler half-widths of D3 and of the H, K Ca(+) lines obtained in a prominence active phase are much larger than those obtained during a quiet phase. Comparison of the equivalent widths and central intensities of H sub alpha, H sub beta hydrogen and D3 helium lines shows that the values increase in the active phase for the D3 lines and decrease for the H sub alpha, H sub beta lines.
Theoretical study of absorption and emission spectra of the monomer of PFBT
NASA Astrophysics Data System (ADS)
Wang, Jing; Gu, Jiande; Leszczynski, Jerzy
Conjugated polymers (CPs) have been used as highly responsive optical sensors for chemical and biological targets. The density functional theory (DFT), the time-dependent density functional theory (TDDFT) and the singly excited configuration interaction (CIS) approach were employed to simulate the absorption and emission spectra of a model monomer unit of the typical CP, poly[9,9'-bis-(6'- N, N, N-trimethylammonium)hexyl]fluorene-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT). Various basis sets were applied in the calculations and their effects on the predictions for the optical properties of FBT are discussed. The results suggest that the TD-B3LYP method with basis sets larger than 6-311G(d,p) provides a suitable approach for investigations of the studied system.
Soft x ray emission spectra from laser-irradiated high-Z targets
NASA Astrophysics Data System (ADS)
Mehlman, G.; Burkhalter, P. G.; Newman, D. A.; Ripin, B. H.
X ray data were acquired from mass-limited targets with the Pharos III laser system. Targets, mounted at the tip of thin glass stalks, were microscopic pieces of single or multiple high-Z element composition. The laser irradiance was 4 x 10(exp 14) W/sq cm with about 300J of focused 1.05 microns wavelength laser beam. A convex KAP crystal spectrograph was used for its capability to collect high resolution spectra in the 4 to 20 A soft x ray region. The recorded spectral film densities were microdensitometered and converted by computer-processing to absolute continuum and emission line intensities. The spectral features were identified with the aid of ab-initio atomic structure calculations. The continuum background was evaluated as a source of pseudo-continua for absorption studies of soft x rays.
Expected gamma-ray emission spectra from the lunar surface as a function of chemical composition
NASA Technical Reports Server (NTRS)
Reedy, R. C.; Arnold, J. R.; Trombka, J. I.
The gamma rays emitted from the moon or any similar body carry information on the chemical composition of the surface layer. The elements most easily measured are K, U, Th and major elements such as O, Si, Mg, and Fe. The expected fluxes of gamma ray lines were calculated for four lunar compositions and one chondritic chemistry from a consideration of the important emission mechanisms: natural radioactivity, inelastic scatter, neutron capture, and induced radioactivity. The models used for cosmic ray interactions were those of Reedy and Arnold and Lingenfelter. The areal resolution of the experiment was calculated to be around 70 to 140 km under the conditions of the Apollo 15 and 16 experiments. Finally, a method was described for recovering the chemical information from the observed scintillation spectra obtained in these experiments.
Frequency spectra of cosmic ray air shower radio emission measured with LOPES
A. Nigl
AIMS: We wish to study the spectral dependence of the radio emission from cosmic-ray air showers around 100 PeV (1017 eV). METHODS: We observe short radio pulses in a broad frequency band with the dipole-interferometer LOPES (LOFAR Prototype Station), which is triggered by a particle detector array named Karlsruhe Shower Core and Array Detector (KASCADE). LOFAR is the Low Frequency Array. For this analysis, 23 strong air shower events are selected using parameters from KASCADE. RESULTS: The resulting electric field spectra fall off to higher frequencies. An average electric field spectrum is fitted with an exponential, or alternatively, with a power law. The spectral slope obtained is not consistent within uncertainties and it is slightly steeper than the slope obtained from Monte Carlo simulations based on air showers simulated with CORSIKA (Cosmic Ray Simulations for KASCADE). One of the strongest events was measured during thunderstorm activity in the vicinity of LOPES and shows the longest pulse length measured of 110 ns and a spectral slope of -3.6. CONCLUSIONS: We show with two different methods that frequency spectra from air shower radio emission can be reconstructed on event-by-event basis, with only two dozen dipole antennae simultaneously over a broad range of frequencies. According to the obtained spectral slopes, the maximum power is emitted below 40 MHz. Furthermore, the decrease in power to higher frequencies indicates a loss in coherence determined by the shower disc thickness. We conclude that a broader bandwidth, larger collecting area, and longer baselines, as will be provided by LOFAR, are necessary to further investigate the relation of the coherence, pulse length, and spectral slope of cosmic ray air showers.
Molecular phonons and their absorption/emission spectra from the far-IR to microwaves
NASA Astrophysics Data System (ADS)
Papoular, R.
Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from �20 to more than 104 ?m, depending on molecular size. These spectra are discrete but large assemblies of molecules of the same family, differing only by minor structural details, will produce continua. As such assemblies are expected to exist in regions where dust accumulates, they are bound to contribute to the observed continua underlying the unidentified infrared bands and the 21 ?m band of planetary nebulae as well as to the diffuse galactic emission surveyed by the Planck astronomical satellite and other means. The purpose of this work is to determine, for carbon-rich molecules, the intensity of such continua and their extent into the millimetric range, and to evaluate their detectability in this range. The rules governing the spectral distributions of phonons are derived and shown to differ from those which obtain in the solid state. Their application allows the extinction cross-section per H atom, and its maximum wavelength, to be determined as a function of molecular size and dimensionality. Chemical modelling of more than 15 large molecules illustrates these results. It is found that the maximum phonon wavelength of a 2D structure increases roughly as the square of its larger dimension. Spectral energy distributions were computed as far as 4000 ?m, for molecules up to 50 � in length.
Theoretical study on absorption and emission spectra of pyrrolo-C analogues
NASA Astrophysics Data System (ADS)
Liu, Hongxia; Liu, Jianhua; Yang, Yan; Li, Yan; Wang, Haijun
Fluorescent nucleoside analogues have attracted much attention in studying the structure and dynamics of nucleic acids in recent years. In the present work, we use theoretical calculations to investigate the structural and optical properties of Pyrrolo-C (PyC) and its analogues which are modified via the conjugation or fusion of different aromatic ring to the PyC core. We also consider the effects of aqueous solution and base pairing. The results show that the fluorescent pyrrolo-C analogues can pair with guanosine to form stable H-bonded WC base pairs. The calculated absorption peaks of modified deoxyribonucleosides agree well with the measured data. The absorption and emission maxima of the pyrrolo-C analogues are greatly red shifted compared with nature C. The solvent effects can induce wavelength blue shift and increase the oscillator strengths in both the absorption and emission spectra. With regard to the WC base pairs, the B3LYP functional reveals that the lowest energy transitions of modified GC base pairs are charge transfer excitation while the CAM-B3LYP functional predicts that all the lowest transitions are localised on the pyrrolo-C analogues. The M062X and CAM-B3LYP functionals show good agreement with respect to both the value of the lowest energy transitions as well as the oscillator strengths.
Package for Interactive Analysis of Line Emission (Analysis of UV-X-Ray High-Resolution Emission Spectra)
NASA Technical Reports Server (NTRS)
Kashyap, Vinay; Hunter, Paul (Technical Monitor)
PINTofALE is an IDL based package to analyze high-resolution grating spectra. The first version was made available to the public on 3 February 2001. Since then we have carried out numerous changes, and the current release is version 1.5, released on 9 October 2002. The changes include upgrades to handle higher versions of IDL, the new version of the CHIANTI database (v4), major enhancements in user-friendliness, improved handling of response matrices, the ability to handle 24-bit color, access to the Atomic Plasma Emission Database (APED), and beta releases of Markov Chain Monte Carlo (MCMC) based DEM fitting routines. Plans for the future include: inclusion of MCMC techniques in the fitting programs, enhanced graphics capabilities, an overhaul of the line and continuum database structure, and bug fixes. In September 2002, we hired a data analyst (LiWei Lin) to work on PINTofALE. Mr.Lin is concentrating on incorporating MCMC as well as simpler Monte-Carlo techniques, fast RMF convolution, etc., into the code base, as well as reviewing the existing documentation and searching for bugs. A detailed description of the package, together with fairly detailed documentation, example walks-throughs, and downloadable tar files, are available on-line from http://hea-www. harvard.edu/PINTofALE/
Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter.
Chen, Wen; Westerhoff, Paul; Leenheer, Jerry A; Booksh, Karl
Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the > 10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation-emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation-emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (phi(i,n)). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet-visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 hydrophobic or hydrophilic acid, neutral, and base DOM fractions plus nonfractionated DOM from wastewater effluents and rivers in the southwestern United States. DOM fractions fluoresced in one or more EEM regions. The highest cumulative EEM volume (phi(T,n) = sigma phi(i,n)) was observed for hydrophobic neutral DOM fractions, followed by lower phi(T,n) values for hydrophobic acid, base, and hydrophilic acid DOM fractions, respectively. An extracted wastewater biomass DOM sample contained aromatic protein- and humic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presence of specific aromatic compounds (as indicated by solid-state 13C NMR and FTIR data) resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM. PMID:14717183
Fluorescence Excitation-Emission Matrix Regional Integration to Quantify Spectra for Dissolved Organic Matter
Chen, W.; Westerhoff, P.; Leenheer, J.A.; Booksh, K.
Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation-emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation-emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (??i,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet-visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 hydrophobic or hydrophilic acid, neutral, and base DOM fractions plus nonfractionated DOM from wastewater effluents and rivers in the southwestern United States. DOM fractions fluoresced in one or more EEM regions. The highest cumulative EEM volume (??T,n = ????i,n) was observed for hydrophobic neutral DOM fractions, followed by lower ??T,n values for hydrophobic acid, base, and hydrophilic acid DOM fractions, respectively. An extracted wastewater biomass DOM sample contained aromatic protein- and humic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presence of specific aromatic compounds (as indicated by solid-state 13C NMR and FTIR data) resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM.
Infrared Space Observatory Spectra of R Coronae Borealis Stars. I. Emission Features in the Interval 3 - 25 microns
David L. Lambert; N. Kameswara Rao; Gajendra Pandey; Inese I. Ivans
Infrared Space Observatory 3 - 25 $\\mu$m spectra of the R Coronae Borealis stars V854 Cen, R CrB, and RY Sgr are presented and discussed. Sharp emission features coincident in wavelengths with the well known Unidentified Emission Features are present in the spectrum of V854 Cen but not of R CrB or RY Sgr. Since V854 Cen is not particularly H-poor and has a 1000 times more H than the other stars, the emission features are probably from a carrier containing hydrogen. There is a correspondence between the features and emission from laboratory samples of hydrogenated amorphous carbon. A search for C$_{60}$ in emission or absorption proved negative. Amorphous carbon particles account for the broad emission features seen between 6 - 14 $\\mu$m in the spectrum of each star.
Atomic emission of anhydrous hydrogen bromide: Spectra from 200 to 900 nm by sealed inductively coupled plasma-atomic emission spectroscopy
Reha K. Tepe; Tracey Jacksier; Ramon M. Barnes
Anhydrous hydrogen bromide, at concentrations of up to 25%, has been introduced into a sealed inductively coupled plasma system for spectrochemical analysis. The emission spectra of 15% anhydrous hydrogen bromide is reported over the spectral range of 200 to 900 nm from an enclosed inductively coupled plasma discharge operated at atmospheric pressure and 1.1 kW. More than 140 atomic Br
F�rster resonance energy transfer, absorption and emission spectra in multichromophoric systems. III. Exact stochastic path integral evaluation.
Moix, Jeremy M; Ma, Jian; Cao, Jianshu
A numerically exact path integral treatment of the absorption and emission spectra of open quantum systems is presented that requires only the straightforward solution of a stochastic differential equation. The approach converges rapidly enabling the calculation of spectra of large excitonic systems across the complete range of system parameters and for arbitrary bath spectral densities. With the numerically exact absorption and emission operators, one can also immediately compute energy transfer rates using the multi-chromophoric F�rster resonant energy transfer formalism. Benchmark calculations on the emission spectra of two level systems are presented demonstrating the efficacy of the stochastic approach. This is followed by calculations of the energy transfer rates between two weakly coupled dimer systems as a function of temperature and system-bath coupling strength. It is shown that the recently developed hybrid cumulant expansion (see Paper II) is the only perturbative method capable of generating uniformly reliable energy transfer rates and emission spectra across a broad range of system parameters. PMID:25747062
The possible mechanism of the formation of emission clouds radiating broad lines in the spectra of active galactic nuclei
A. S. Zentsova
The present study proves the hypothesis that the formation of emission clouds radiating the permitted lines in the spectra of active galaxies takes place in the outer parts of an accretion disk around a massive black hole. These parts of the disk become self-gravitating and may disintegrate into fragments. The nonlinear effects in the disk must provoke the slow drift
Interpretation of the emission line spectra of Seyfert 2 galaxies by multi-component photoionization models
Stefanie Komossa; Hartmut Schulz
We present multi-component photoionization models allowing for local density inhomogeneities in the NLR to interpret the emission line spectra of Seyfert 2 galaxies. This approach leads to a successful match of a large set of line intensities from the UV to the NIR. In particular, the hitherto elusive NIR features [SIII]9062+9531 as well as high-ionization lines like [FeVII] are consistently fitted. The predictions of CIII] and CIV are considerably improved. From the detailed analysis of single-component photoionization models we derive the minimal radial extent of the NLR and the necessary span in density. Furthermore, we determine constraints on suggestions made about the role of matter-bounded clouds, and on proposed explanations for large [OIII]4363/5007 ratios (the so-called `temperature problem'), and assess the usability of some emission-line ratios as indicators of the ionization parameter. We find that a systematic variation of the cloud column densities in a population of matter-bounded clouds is inconsistent with the trends and correlations exhibited by the emission lines in the diagnostic diagrams. Concerning the temperature problem, the only possibility that leads to an overall consistency with the strengths of all other observed emission lines is subsolar metal abundances (as compared to e.g. the presence of dust, the existence of a high-density component, or matter-bounded clouds). In addition, the consequences of the presence of (Galactic-ISM-like) dust internal to the clouds were investigated. These models alleviate the [OIII]-ratio problem but did not lead to overall consistent fits. In our final model series, the NLR is composed of a mixture of metal-depleted (0.5 x solar) clouds with a radius-independent range in densities (10^2 to 10^5 cm^-3) distributed over a range of distances from the nucleus (galactocentric radii from at least $\\sim$ 10^{20} cm to 10^{21.5} cm, for $Q_{tot} = 10^{54}$ s^{-1}). In order to encompass the observed range of each line intensity relative to H$\\beta$, it turns out to be necessary to vary the spectral energy distribution incident on the clouds, qualitatively confirming the findings of Ho et al. (1993). We found a successful continuum sequence by adding an increasing contribution of a hot black body ($T \\approx 200000$ K) to a steep powerlaw ($\\alpha_{uv-x} \\approx -2$). These continua imply that low and high-excitation objects differ in the strength but not in the basic shape of the EUV bump.
K-alpha X-ray Thomson Scattering From Dense Plasmas
Kritcher, Andrea L. [Nuclear Engineering Department, University of California Berkeley, Berkeley, CA 94709 (United States); Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Neumayer, Paul; Castor, John; Doeppner, Tilo; Landen, Otto L.; Ng, Andrew; Pollaine, Steve; Price, Dwight; Glenzer, Siegfried H. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Falcone, Roger W.; Ja Lee, Hae [Physics Department, University of California Berkeley, Berkeley, CA 94709 (United States); Lee, Richard W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Physics Department, University of California Berkeley, Berkeley, CA 94709 (United States); Morse, Edward C. [Nuclear Engineering Department, University of California Berkeley, Berkeley, CA 94709 (United States)
Spectrally resolved Thomson scattering using ultra-fast K-alpha x rays has measured the compression and heating of shocked compressed matter. The evolution and coalescence of two shock waves traveling through a solid density LiH target were characterized by the elastic scattering component. The density and temperature at shock coalescence, 2.2 eV and 1.7x10{sup 23} cm{sup -3}, were determined from the plasmon frequency shift and the relative intensity of the elastic and inelastic scattering features in the collective scattering regime. The observation of plasmon scattering at coalescence indicates a transition to the dense metallic state in LiH. The density and temperature regimes accessed in these experiments are relevant for inertial confinement fusion experiments and for the study of planetary formation.
K-(alpha) X-ray Thomson Scattering From Dense Plasmas
Kritcher, A L; Neumayer, P; Castor, J; Doppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H
Spectrally resolved Thomson scattering using ultra-fast K-{alpha} x-rays has measured the compression and heating of shocked compressed matter. The evolution and coalescence of two shock waves traveling through a solid density LiH target were characterized by the elastic scattering component. The density and temperature at shock coalescence, 2.2 eV and 1.7 x 10{sup 23}cm{sup -3}, were determined from the plasmon frequency shift and the relative intensity of the elastic and inelastic scattering features in the collective scattering regime. The observation of plasmon scattering at coalescence indicates a transition to the dense metallic state in LiH. The density and temperature regimes accessed in these experiments are relevant for inertial confinement fusion experiments and for the study of planetary formation.
Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pits
NASA Astrophysics Data System (ADS)
Pan, Yong-Le; Houck, Joshua D. T.; Clark, Pamela A.; Pinnick, Ronald G.
A single-particle fluorescence spectrometer (SPFS) and an aerodynamic particle sizer were used to measure the fluorescence spectra and particle size distribution from the particulate emissions of 12 different burning materials in a tube furnace to simulate open-air burning of garbage. Although the particulate emissions are likely dominated by particles <1 ?m diameter, only the spectra of supermicron particles were measured here. The overall fluorescence spectral profiles exhibit either one or two broad bands peaked around 300-450 nm within the 280-650 nm spectral range, when the particles are illuminated with a 263-nm laser. Different burning materials have different profiles, some of them (cigarette, hair, uniform, paper, and plastics) show small changes during the burning process, and while others (beef, bread, carrot, Styrofoam, and wood) show big variations, which initially exhibit a single UV peak (around 310-340 nm) and a long shoulder in visible, and then gradually evolve into a bimodal spectrum with another visible peak (around 430-450 nm) having increasing intensity during the burning process. These spectral profiles could mainly derive from polycyclic aromatic hydrocarbons with the combinations of tyrosine-like, tryptophan-like, and other humic-like substances. About 68 % of these single-particle fluorescence spectra can be grouped into 10 clustered spectral templates that are derived from the spectra of millions of atmospheric aerosol particles observed in three locations; while the others, particularly these bimodal spectra, do not fall into any of the 10 templates. Therefore, the spectra from particulate emissions of burning materials can be easily discriminated from that of common atmospheric aerosol particles. The SFFS technology could be a good tool for monitoring burning pit emissions and possibly for distinguishing them from atmospheric aerosol particles.
Infrared and near infrared emission spectra of TeH and TeD
NASA Astrophysics Data System (ADS)
Yu, Shanshan; Shayesteh, Alireza; Fu, Dejian; Bernath, Peter F.
The vibration-rotation emission spectra for the X2? ground state and the near infrared emission spectra of the X2? 1/2- X2? 3/2 system of the TeH and TeD free radicals have been measured at high resolution using a Fourier transform spectrometer. TeH and TeD were generated in a tube furnace with a DC discharge of a flowing mixture of argon, hydrogen (or deuterium), and tellurium vapor. In the infrared region, for the X2? 3/2 spin component we observed the 1-0, 2-1, and 3-2 vibrational bands for most of the eight isotopologues of TeH and the 1-0 and 2-1 bands for three isotopologues of TeD. For the X2? 1/2- X2? 3/2 transition, we observed the 0-0 and 1-1 bands for TeH and the 0-0, 1-1, and 2-2 bands for TeD. Except for a few lines, the tellurium isotopic shift was not resolved for the X2? 1/2- X2? 3/2 transitions of TeH and TeD. Local perturbations with ? v = 2 between the two spin components of the X2? state of TeH were found: X2? 1/2, v = 0 with X2? 3/2, v = 2; X2? 1/2, v = 1 with X2? 3/2, v = 3. The new data were combined with the previous data from the literature and two kinds of fits (Hund's case (a) and Hund's case (c)) were carried out for each of the 10 observed isotopologues: 130TeD, 128TeD, 126TeD, 130TeH, 128TeH, 126TeH, 125TeH, 124TeH, 123TeH, and 122TeH.
Optical and microphysical parameters of the Mt. Pinatubo aerosol as determined from MIPAS-B mid-IR limb emission spectra
G. Echle; T. von Clarmann; H. Oelhaf
High-resolution mid-IR limb emission spectra were recorded during a flight of the Michelson interferometer for passive atmospheric sounding, balloon-borne version (MIPAS-B) from Kiruna, northern Sweden (68�N) on March 14\\/15, 1992. These spectra are affected by the Mt. Pinatubo stratospheric aerosol, which caused an enhanced continuum emission, especially in spectra of low tangent altitudes. Aerosol extinction coefficients were retrieved from MIPAS-B
Inami, H. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Armus, L.; Stierwalt, S.; D�az-Santos, T.; Surace, J.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Groves, B. [Max Planck Institute for Astronomy, K�nigstuhl 17, D-69117 Heidelberg (Germany); Kewley, L. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Petric, A. [Department of Astronomy, California Institute of Technology, MS 320-47, Pasadena, CA 91125 (United States); Rich, J. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Haan, S. [CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Mazzarella, J.; Lord, S. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Appleton, P. [NASA Herschel Science Center, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Spoon, H. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Matsuhara, H., E-mail: firstname.lastname@example.com [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan); and others
We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne V], [Ne III], [S III]{sub 18.7{sub ?m}}, [O IV], [Fe II], [S III]{sub 33.5{sub ?m}}, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne V]/[Ne II] line flux ratios and equivalent width of the 6.2 ?m polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S IV]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z{sub ?}, and ionization parameters of 2-8 � 10{sup 7} cm s{sup �1}. Based on the [S III]{sub 33.5{sub ?m}}/[S III]{sub 18.7{sub ?m}} ratios, the electron density in LIRG nuclei is typically one to a few hundred cm{sup �3}, with a median electron density of ?300 cm{sup �3}, for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM ?600 km s{sup �1}) and five show clear differences in the velocities of the [Ne III] or [Ne V] emission lines, relative to [Ne II], of more than 200 km s{sup �1}. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential, suggesting the possibility of a compact energy source and stratified interstellar medium in their nuclei. We confirm a strong correlation between the sum of the [Ne II]{sub 12.8{sub ?m}} and [Ne III]{sub 15.5{sub ?m}} emission, as well as [S III]{sub 33.5{sub ?m}}, with both the infrared luminosity and the 24 ?m warm dust emission measured from the spectra, consistent with all three lines tracing ongoing star formation. Finally, we find no correlation between the hardness of the radiation field or the emission-line width and the ratio of the total infrared to 8 ?m emission (IR8), a measure of the strength of the starburst and the distance of the LIRGs from the star-forming main sequence. This may be a function of the fact that the infrared luminosity and the mid-infrared fine-structure lines are sensitive to different timescales over the starburst, or that IR8 is more sensitive to the geometry of the region emitting the warm dust than the radiation field producing the H II region emission.
Synergistic approach to modeling X-ray spectra
Liedahl, D.A., LLNL
Plasma emission models used in X-ray astronomy need to simulate X-ray spectra from at least thirteen elements. Development of comprehensive models requires large-scale calculations; for example, Fe M-shell spectra, K{alpha} fluorescence from near-neutral ions, and dielectronic recombination satellite spectra from L-shell ions. Current and recent missions (EUVE, ASCA, DXS, etc.) have already demonstrated the need for major, rapid improvements in spectral models. The high-resolution spectra to be acquired with the next generation of X- ray observatories (AXAF, XMM, Astro-E) promise to push spectral models to their limits. Essential to ensuring the quality of calculations used in spectral codes is corroboration in the laboratory, where controlled and precisely measured plasma conditions can be attained. To this end, we are capitalizing on a three-way synergistic relationship that links astrophysical observations, atomic modeling, and experiments using the LLNL Electron Beam Ion Trap (EBIT). After providing a brief orientation concerning the role of plasma emission models in X-ray astronomy, we discuss one example of this interplay.
Effect of heat treatment on the far-infrared emission spectra and fine structures of black tourmaline.
Meng, Junping; Liang, Jinsheng; Liu, Jie; Ding, Yan; Gan, Kun
Mineral black tourmaline powders were heat-treated at different temperatures. Their crystal structure was studied by X-ray diffractometer. Their infrared absorption and emission spectra before and after the heat treatment were analyzed by the Fourier transform infrared spectrometer. The corresponding fine structures were discussed in detail. The results showed that the powders possessed higher infrared emissivity at the band where they showed stronger infrared absorption. However, there is no certain correlation between the peak intensity of infrared absorption and emissivity values at the same frequency. Because of the crystal shrinkage of c-axis, the electronic transitions were stimulated between different energy levels, and the abilities of infrared absorption and emission were enhanced with increasing the temperature of heat treatment. PMID:24734598
Mid-infrared emission and Raman spectra analysis of Er3+-doped oxyfluorotellurite glasses.
Chen, Fangze; Xu, Shaoqiong; Wei, Tao; Wang, Fengchao; Cai, Muzhi; Tian, Ying; Xu, Shiqing
This paper reports on the spectroscopic and structural properties in Er3+-doped oxyfluorotellurite glasses. The compositional variation accounts for the evolutions of Raman spectra, Judd-Ofelt parameters, radiative properties, and fluorescent emission. It is found that, when maximum phonon energy changes slightly, phonon density plays a crucial role in quenching the 2.7�?m emission generated by the Er3+?I11/24?I413/2 transition. The comparative low phonon density contributes strong 2.7�?m emission intensity. The high branching ratio (18.63%) and large emission cross section (0.95�10-20??cm2) demonstrate that oxyfluorotellurite glass contained with 50�mol.% TeO2 has potential application in the mid-infrared region laser. PMID:25967322
Excitation Emission Matrix Spectra (EEMS) of Chromophoric Dissolved Organic Matter Produced during Microbial Incubation
NASA Astrophysics Data System (ADS)
McDonald, N.; Nelson, N. B.; Parsons, R.
The chromophoric or light-absorbing fraction of dissolved organic matter (CDOM) is present ubiquitously in natural waters and has a significant impact on ocean biogeochemistry, affecting photosynthesis and primary production as well direct and indirect photochemical reactions (Siegel et al., 2002; Nelson et al., 2007). It has been largely researched in the past few decades, however the exact chemical composition remains unknown. Instrumental methods of analysis including simultaneous excitation-emission fluorescence spectra have allowed for further insight into source and chemical composition. While certain excitation-emission peaks have been associated with ';marine' sources, they have not been exclusively linked to bacterial production of CDOM (Coble, 1996; Zepp et al., 2004). In this study, ';grazer diluted' seawater samples (70% 0.2?m filtered water; 30% whole water) were collected at the Bermuda Atlantic Time Series (BATS) site in the Sargasso Sea (31� 41' N; 64� 10' W) and incubated with an amendment of labile dissolved organic carbon (10?M C6H12O6), ammonium (1?M NH4Cl) and phosphate (0.1?M K2HPO4) to facilitate bacterial production. These substrates and concentrations have been previously shown to facilitate optimum bacterial and CDOM production (Nelson et al., 2004). Sample depths were chosen at 1m and 200m as water at these depths has been exposed to UV light (the Subtropical Mode Water at 200m has been subducted from the surface) and therefore has low initial concentrations of CDOM. After the samples were amended, they were incubated at in-situ temperatures in the dark for 72 hours, with bacteria counts, UV-Vis absorption and EEMS measurements taken at 6-8 hour intervals. Dissolved organic carbon (DOC) measurements were collected daily. For the surface water experiment specific bacteria populations were investigated using Fluorescence In-Situ Hybridization (FISH) analysis. Results showed a clear production of bacteria and production of CDOM, which can be linked to this bacterial production. FISH analysis showed percentage abundance of Pelagibacter ubique (SAR 11) and of Alteromonas. On-going and future work will ascertain if specific microbial communities produce CDOM more readily than others, and if these different populations produce varying fluorescence peaks, thus indicating a range of chromophoric groups being produced by bacteria. An additional suite of probes will be used for further FISH analysis to identify percentages of other populations, and seasonal/temporal variations will be investigated.
HST-COS Observations of AGN. I. Ultraviolet Composite Spectra of the Ionizing Continuum and Emission Lines
Shull, J Michael; Danforth, Charles W
The ionizing fluxes from quasars and other active galactic nuclei (AGN) are critical for interpreting the emission-line spectra of AGN and for photoionization and heating of the intergalactic medium (IGM). Using ultraviolet spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we have directly measured the rest-frame ionizing continua and emission lines for 22 AGN. Over the redshift range 0.026 < z < 1.44, COS samples the Lyman continuum and many far-UV emission lines (Lya 1216, C IV 1549, Si IV/OIV] 1400, N V 1240, O VI 1035). Strong EUV emission lines with 14-22 eV excitation energies (Ne VIII 770,780, Ne V 569, O II 834, O III 833, 702, O IV 788,608,554, O V 630, N III 685) suggest the presence of hot gas in the broad emission-line region. The rest-frame continuum, F_nu \\sim nu^{alpha_nu}, shows a break at wavelengths below 1000 A, with spectral index alpha_nu = -0.68 +/- 0.14 in the FUV (1200-2000 A) steepening to alpha_nu = -1.41 +/- 0.21 in the EUV (500-1000 A). T...
Infrared Space Observatory Spectra of R Coronae Borealis Stars. I. Emission Features in the Interval 3 - 25 microns
David L. Lambert; N. Kameswara Rao; Gajendra Pandey; Inese I. Ivans
Infrared Space Observatory 3 - 25 $\\\\mu$m spectra of the R Coronae Borealis\\u000astars V854 Cen, R CrB, and RY Sgr are presented and discussed. Sharp emission\\u000afeatures coincident in wavelengths with the well known Unidentified Emission\\u000aFeatures are present in the spectrum of V854 Cen but not of R CrB or RY Sgr.\\u000aSince V854 Cen is not particularly
Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5558: Detection of Strong Narrow Components
NASA Technical Reports Server (NTRS)
Crenshaw, D. Michael; Boggess, Albert; Wu, Chi-Chao
Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Ly alpha, C IV 1549, and C III 1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II 2798 is very weak or absent.
Time-resolved measurements of near infrared emission spectra from explosions: Pure pentaerythritol tetranitrate and its mixtures containing silver and aluminum particles
NASA Astrophysics Data System (ADS)
Koch, Jon D.; Piecuch, Scott; Lightstone, James M.; Carney, Joel R.; Hooper, Joe
Measurements of chemical transients and thermodynamic conditions are difficult to obtain yet fundamentally important in understanding the behavior of explosives. We have constructed a fast near infrared (NIR) spectrometer and have made temporally and spectrally-resolved emission measurements during postdetonation combustion of pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10 wt % microparticles composed of silver (Ag) and aluminum (Al). We have observed postdetonation PETN emission spectra between 750 and 1500 nm at rates up to 46 992 spectra/s. The instrument captures the highly structured spectra immediately following breakout as well as the longer-lived broadband NIR emission signals from hot particles. The early spectra reveal spectral signatures related to PETN and the reacting constituents of the particles. The later spectra provide a means to infer the gray-body temperature history of the particles.
The effect of Fe, Cu, and Si impurities on the formation of emission spectra in bulk ZnO crystals
Mezdrogina, M. M., E-mail: firstname.lastname@example.com; Danilevskii, E. Yu.; Kuz'min, R. V.; Poletaev, N. K.; Trapeznikova, I. N. [Ioffe Physicotechnical Institute (Russian Federation); Chukichev, M. V. [Moscow State University (Russian Federation); Bordovskii, G. A.; Marchenko, A. V. [Russian State Pedagogical University (Russian Federation); Eremenko, M. V. [St. Petersburg State Polytechnical University (Russian Federation)
On the basis of the results of complex investigations (photoluminescence, x-ray fluorescence, and infrared spectroscopy), the features of emission-spectra formation are shown under the change in the type (Fe, Cu, and Si) and concentration of background impurities appearing during both growth and treatment of bulk crystals by grinding and polishing. Special attention is given to the concentration and types of bonds with hydrogen-the basic impurity preventing the formation of crystals with the p-type conductivity.
Drastic emission-spectra changes in a semiconductor laser owing to optical feedback from an optical connector
Matsuura, M.; Tanifuji, T.; Yamamoto, Y.
The time-averaged longitudinal-mode power of a semiconductor laser coupled to fiber changes drastically when an external force is applied to a multimode fiber terminated with an optical connector. No emission-spectra changes have been observed in the case of a single-mode fiber. This phenomenon is considered to be induced by the wavelength-dependent change of the reflected field speckle intensity coupled into the laser-active region.
CO 2 line mixing in MIPAS limb emission spectra and its influence on retrieval of atmospheric parameters
B. Funke; G. P. Stiller; T. Von Clarmann; G. Echle; H. Fischer
Aboard the European ENVISAT polar platform, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) i.r. spectrometer will scan across the limb in order to record high resolution emission spectra. In the course of the definition of micro-windows for retrieval of line of sight, temperature and trace constituents, the spectral and altitudinal regions where CO2 Q-branch line mixing has to be
Global stratospheric HOCl distributions retrieved from infrared limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)
T. von Clarmann; N. Glatthor; U. Grabowski; M. H�pfner; S. Kellmann; A. Linden; Gizaw Mengistu Tsidu; M. Milz; T. Steck; G. P. Stiller; H. Fischer; B. Funke
Vertical profiles of stratospheric HOCl were retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the Envisat research satellite. These are the first HOCl measurements with global coverage. The nu2 transitions between 1215.725 and 1275.550 cm-1 were used for inference of the vertical profiles. The maximal volume mixing ratios were found in the
Ultrafast K-(alpha) X-ray Thomson Scattering from Shock Compressed Lithium Hydride
Kritcher, A L; Neumayer, P; Castor, J; Doeppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Holst, B; Redmer, R; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H
Spectrally and temporally resolved x ray Thomson scattering using ultrafast Ti K-{alpha} x-rays has provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 nanosecond heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models. Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of three times solid density. The quality of data achieved in these experiments demonstrates the capability for single-shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets for experiments such as on the National Ignition Facility (NIF), LLNL.
Ultrafast K{alpha} x-ray Thomson scattering from shock compressed lithium hydride
Kritcher, A. L. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Nuclear Engineering Department, University of California Berkeley, Berkeley, California 94709 (United States); Neumayer, P.; Castor, J.; Doeppner, T.; Landen, O. L.; Ng, A.; Pollaine, S.; Price, D.; Glenzer, S. H. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Falcone, R. W.; Lee, H. J. [Physics Department, University of California Berkeley, Berkeley, California 94709 (United States); Lee, R. W. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Physics Department, University of California Berkeley, Berkeley, California 94709 (United States); Holst, B.; Redmer, R. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Morse, E. C. [Nuclear Engineering Department, University of California Berkeley, Berkeley, California 94709 (United States)
Spectrally and temporally resolved x-ray Thomson scattering using ultrafast Ti K{alpha} x rays has provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 ns heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models. Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of 3 times solid density. The quality of data achieved in these experiments demonstrates the capability for single shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets for experiments such as on the National Ignition Facility, Lawrence Livermore National Laboratory.
Synchrotron emission in short scale magnetic field as possible explanation to prompt emission spectra of Gamma-Ray bursts
Pe�r, A; Pe'er, Asaf; Zhang, Bing
Synchrotron emission is believed to be a major radiation mechanism during gamma-ray bursts (GRB's) prompt emission phase. A significant drawback of this assumption is that the theoretical predicted spectrum, calculated within the framework of the ``internal shocks'' scenario using the standard assumption that the magnetic field maintains a steady value throughout the shocked region, leads to a slope F_\
Comparison of explicit calculations for n = 3 to 8 dielectronic satellites of the FeXXV K. alpha. resonance line with experimental data from the Tokamak Fusion Test Reactor
Decaux, V.; Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Park, H. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Bhalla, C.P. (Kansas State Univ., Manhattan, KS (United States). Dept. of Physics)
Dielectronic satellite spectra of the FeXXV K{alpha} resonance line observed from the Tokamak Fusion Test Reactor (TFTR) plasmas have been compared with recent explicit calculations for the n = 3 to 8 dielectronic satellites as well as the earlier theoretical predictions, which were based on the 1/n{sup 3} scaling law for n > 4 satellites. The analysis has been performed by least-squares fits of synthetic spectra to the experimental data. The synthetic spectra constructed from both theories are in good agreement with the observed data. However, the electron temperature values obtained from the fit of the present explicit calculations are in better agreement with independent measurements. 20 refs., 4 figs.
Vibration-induced structures in scanning tunneling microscope light emission spectra of Ni(1 1 0)-streaky (1 � 2)-H
NASA Astrophysics Data System (ADS)
Uehara, Y.; Ushioda, S.
We have measured the scanning tunneling microscope (STM) light emission spectra of Ni(1 1 0)-streaky (1 � 2) surfaces. When the tip was fixed over atomic hydrogen adsorbed on the surfaces, two types of vibration-induced structure were observed in the STM light emission spectra. One is the periodic fine structures that were already reported in our previous paper [Y. Uehara, S. Ushioda, Phys. Rev. Lett. 92 (2004) 066102] and the other newly found in the present experiments is a stepwise structure that is located at the vibrational energy of hydrogen below the cutoff energy of the STM light emission. They are ascribed to different excitation mechanisms of the vibration in the STM light emission process; the periodic fine structures appear when the vibrating motion is directly excited by the electrons injected from the tip. Conversely, the stepwise structure is observed when it is excited by the electromagnetic fields confined in the tip-sample gap, i.e., by localized surface plasmons.
Analysis of H2 Emission from Mira B in UV Spectra from HST
Brian E. Wood; Margarita Karovska; John C. Raymond
We analyze Ly-alpha fluoresced H2 lines observed in the UV spectrum of Mira B. We identify 13 different sequences fluoresced by 13 different H2 transitions within the Ly-alpha line. The observed H2 line ratios within these sequences imply significant line opacity, so we use a Monte Carlo radiative transfer code to model the line ratios, correcting for opacity effects. We find the observed line ratios can best be reproduced by assuming that the H2 is fluoresced in a layer between the observer and Mira B with a temperature and column density of T=3600 K and log N(H2)=17.3, respectively. The strengths of H2 absorption features within the Ly-alpha line are roughly consistent with this temperature and column. We use the total flux fluoresced within the 13 sequences to infer the Ly-alpha profile seen by the H2. In order to explain differences between the shape of this and the observed profile, we have to assume that the observed profile suffers additional interstellar (or circumstellar) H I Ly-alpha absorption with a column density of about log N(H I)=20.35. We also have to assume that the observed profile is about a factor of 2.5 lower in flux than the profile seen by the H2, and a couple possible explanations for this behavior are presented. Several lines of evidence lead us to tentatively attribute the fluoresced emission to H2 that is heated in a photodissociation front within Mira A's wind a few AU from Mira B, although it is possible that interaction between the winds of Mira A and B may also play a role in heating the H2. We estimate a Mira B mass loss rate of 5e-13 solar masses per year and a terminal velocity of 250 km/s, based on wind absorption features in the Mg II h & k lines. We note, however, that the wind is variable and IUE Mg II spectra suggest significantly higher mass loss rates during the IUE era.
Tingay, S. J.; Wayth, R. B., E-mail: firstname.lastname@example.com [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA (Australia)
We have examined a subset of 11 active galactic nuclei (AGNs) drawn from a sample of 87 objects that possess double-peaked optical emission line spectra, as put forward by Wang et al. and are detectable in the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey at radio wavelengths. The double-peaked nature of the optical emission line spectra has been suggested as evidence for the existence of binary black holes in these AGNs, although this interpretation is controversial. We make a simple suggestion that direct evidence of binary black holes in these objects could be searched for in the form of dual sources of compact radio emission associated with the AGNs. To explore this idea, we have used the Very Long Baseline Array to observe these 11 objects from the Wang et al. sample. Of the 11 objects, we detect compact radio emission from two, SDSS J151709+335324 and SDSS J160024+264035. Both objects show single components of compact radio emission. The morphology of SDSS J151709+335324 is consistent with a recent comprehensive multi-wavelength study of this object by Rosario et al. Assuming that the entire sample consists of binary black holes, we would expect of order one double radio core to be detected, based on radio wavelength detection rates from FIRST and very long baseline interferometry surveys. We have not detected any double cores, thus this work does not substantially support the idea that AGNs with double-peaked optical emission lines contain binary black holes. However, the study of larger samples should be undertaken to provide a more secure statistical result, given the estimated detection rates.
Semiclassical molecular dynamics computation of spontaneous light emission in the condensed phase: Resonance Raman spectra
Apkarian, V. Ara
: Resonance Raman spectra M. Ovchinnikov Department of Chemistry and Henry Eyring Center for Theoretical of Chemistry and Henry Eyring Center for Theoretical Chemistry, 315 South 1400 East Room 2020, University
Aerosol-fluorescence spectrum analyzer: real-time measurement of emission spectra of airborne biological particles
NASA Astrophysics Data System (ADS)
Hill, Steven C.; Pinnick, Ronald G.; Nachman, Paul; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.
We have assembled an aerosol-fluorescence spectrum analyzer (AFS), which can measure the fluorescence spectra and elastic scattering of airborne particles as they flow through a laser beam. The aerosols traverse a scattering cell where they are illuminated with intense (50 kW/cm 2) light inside the cavity of an argon-ion laser operating at 488 nm. This AFS can obtain fluorescence spectra of individual dye-doped polystyrene microspheres as small as 0.5 mu m in diameter. The spectra obtained from microspheres doped with pink and green-yellow dyes are clearly different. We have also detected the fluorescence spectra of airborne particles (although not single particles) made from various
On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes
NASA Astrophysics Data System (ADS)
Wehrle, Marius; �ulc, Miroslav; Van�?ek, Ji?�
Vibrationally resolved spectra provide a stringent test of the accuracy of theoretical calculations. We combine the thawed Gaussian approximation (TGA) with an on-the-fly ab initio (OTF-AI) scheme to calculate the vibrationally resolved emission spectra of oligothiophenes with up to five rings. The efficiency of the OTF-AI-TGA permits treating all vibrational degrees of freedom on an equal footing even in pentathiophene with 105 vibrational degrees of freedom, thus obviating the need for the global harmonic approximation, popular for large systems. Besides reproducing almost perfectly the experimental emission spectra, in order to provide a deeper insight into the associated physical and chemical processes, we also develop a novel systematic approach to assess the importance and coupling between individual vibrational degrees of freedom during the dynamics. This allows us to explain how the vibrational line shapes of the oligothiophenes change with increasing number of rings. Furthermore, we observe the dynamical interplay between the quinoid and aromatic characters of individual rings in the oligothiophene chain during the dynamics and confirm that the quinoid character prevails in the center of the chain.
Fluorescence and stimulated emission S1 --> S0 spectra of acetylene: Regular and ergodic regions
Evan Abramson; Robert W. Field; Dan Imre; K. K. Innes; James L. Kinsey
The S1 ? S0 transition of acetylene has been studied by spontaneous and stimulated emission. In the spontaneous emission studies, we report new data on low-resolution dispersed fluorescence from an unrelaxed single rotational level of S1. Transitions into S0 levels from the zero-point level up to ?28 000 cm?1 of vibrational energy are reported. Earlier investigations of the emission from
The Case for General Relativistic Effects in the Fe K(alpha) Profile of an Active Galaxy
NASA Technical Reports Server (NTRS)
Turner, T. J.; Mushotzky, R.; Yaqoob, T.; George, I. M.; Snowden, S. L.; Netzer, H.; Kraemer, S. B.; Nandra, K.; Chelouche, D.; White, Nicholas E. (Technical Monitor)
We present results from a simultaneous Chandra HETG (High Energy Transmission Grating) and XMM (X-ray Multi-mirror Mission)-Newton observation of NGC 3516. We find evidence for several narrow components of Fe K(alpha) along with a broad line. We consider the possibility that the lines arise in a blob of material ejected from the nucleus with velocity of approximately 0.25c. We also consider an origin in a neutral accretion disk, suffering enhanced illumination at 35 and 175 R(sub g), perhaps due to magnetic reconnection. The presence of these narrow features indicates there is no Comptonizing region along the line-of-sight to the nucleus. This in turn is compelling support for the hypothesis that broad Fe K(alpha) components are, in general, produced by strong gravity.
Effects of Incident Electron Fluence and Energy on the Election Yield Curves and Emission Spectra of Dielectrics
NASA Technical Reports Server (NTRS)
Sim, Alec; Dennison, J. R.; Thomson, Clint
We present an experimental study of evolution of electron emission yields and spectra as a result of internal charge build up due to electron dose. Reliable total, backscattered and secondary yield curves and electron emission spectra for un-charged insulators using a low fluence, pulsed electron beam (= or < 5 microsec at = or < 3 nA/sq mm or = or < 10(exp 5) e/sq mm per pulse) with low energy electron and UV flooding to neutralize the charging between pulses. Quantifiable changes in yield curves are observed due to < 100 fC/sq mm fluences for several excellent dielectric thin film materials. We find good agreement with a phenomenological argument based on insulator charging predicted by the yield curve; this includes an approximately linear decrease in the magnitude of the yield as incident energies approach the crossover energies and an exponential decrease in yield as accumulated internal charge reduces the landing energy to asymptotically approach a steady state surface charge and unity yield. We also find that the exponential decay of yield curves with fluence exhibit an energy dependent decay constant, alpha(E), over a broad range of incident energies below, between and above the crossover energies. Finally, we present some preliminary physics-based models for this energy dependence and attempt to relate our charging measurements to knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and transport, and how the profile of trapped charge affects the transport and emission of charges from insulators.
Retrieval of temperature and tangent altitude pointing from limb emission spectra recorded from space by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)
T. von Clarmann; N. Glatthor; U. Grabowski; M. H�pfner; S. Kellmann; M. Kiefer; A. Linden; G. M. Tsidu; M. Milz; T. Steck; G. P. Stiller; D. Y. Wang; H. Fischer; B. Funke; S. Gil-L�pez; M. L�pez-Puertas
Retrieval of abundances of atmospheric species from limb infrared emission spectra requires accurate knowledge of the pointing of the instrument in terms of elevation, as well as temperature and pressure profiles. An optimal estimation-based method is presented to infer these quantities from measured spectra. The successful and efficient joint retrieval of these largely correlated quantities depends strongly on the proper
SPITZER IRS spectra of Virgo early type galaxies: detection of stellar silicate emission
A. Bressan; P. Panuzzo; L. Buson; M. Clemens; G. L. Granato; R. Rampazzo; L. Silva; J. R. Valdes; O. Vega; L. Danese
We present high signal to noise ratio Spitzer Infrared Spectrograph observations of 17 Virgo early-type galaxies. The galaxies were selected from those that define the colour-magnitude relation of the cluster, with the aim of detecting the silicate emission of their dusty, mass-losing evolved stars. To flux calibrate these extended sources we have devised a new procedure that allows us to obtain the intrinsic spectral energy distribution and to disentangle resolved and unresolved emission within the same object. We have found that thirteen objects of the sample (76%) are passively evolving galaxies with a pronounced broad silicate feature which is spatially extended and likely of stellar origin, in agreement with model predictions. The other 4 objects (24%) are characterized by different levels of activity. In NGC 4486 (M 87) the line emission and the broad silicate emission are evidently unresolved and, given also the typical shape of the continuum, they likely originate in the nuclear torus. NGC 4636 shows emission lines superimposed on extended (i.e. stellar) silicate emission, thus pushing the percentage of galaxies with silicate emission to 82%. Finally, NGC 4550 and NGC 4435 are characterized by polycyclic aromatic hydrocarbon (PAH) and line emission, arising from a central unresolved region. A more detailed analysis of our sample, with updated models, will be presented in a forthcoming paper.
Hot topic: Innovative lactation-stage-dependent prediction of methane emissions from milk mid-infrared spectra.
Vanlierde, A; Vanrobays, M-L; Dehareng, F; Froidmont, E; Soyeurt, H; McParland, S; Lewis, E; Deighton, M H; Grandl, F; Kreuzer, M; Gredler, B; Dardenne, P; Gengler, N
The main goal of this study was to develop, apply, and validate a new method to predict an indicator for CH4 eructed by dairy cows using milk mid-infrared (MIR) spectra. A novel feature of this model was the consideration of lactation stage to reflect changes in the metabolic status of the cow. A total of 446 daily CH4 measurements were obtained using the SF6 method on 142 Jersey, Holstein, and Holstein-Jersey cows. The corresponding milk samples were collected during these CH4 measurements and were analyzed using MIR spectroscopy. A first derivative was applied to the milk MIR spectra. To validate the novel calibration equation incorporating days in milk (DIM), 2 calibration processes were developed: the first was based only on CH4 measurements and milk MIR spectra (independent of lactation stage; ILS); the second included milk MIR spectra and DIM information (dependent on lactation stage; DLS) by using linear and quadratic modified Legendre polynomials. The coefficients of determination of ILS and DLS equations were 0.77 and 0.75, respectively, with standard error of calibration of 63g/d of CH4 for both calibration equations. These equations were applied to 1,674,763 milk MIR spectra from Holstein cows in the first 3 parities and between 5 and 365 DIM. The average CH4 indicators were 428, 444, and 448g/d by ILS and 444, 467, and 471g/d by DLS for cows in first, second, and third lactation, respectively. Behavior of the DLS indicator throughout the lactations was in agreement with the literature with values increasing between 0 and 100 DIM and decreasing thereafter. Conversely, the ILS indicator of CH4 emission decreased at the beginning of the lactation and increased until the end of the lactation, which differs from the literature. Therefore, the DLS indicator seems to better reflect biological processes that drive CH4 emissions than the ILS indicator. The ILS and DLS equations were applied to an independent data set, which included 59 respiration chamber measurements of CH4 obtained from animals of a different breed across a different production system. Results indicated that the DLS equation was much more robust than the ILS equation allowing development of indicators of CH4 emissions by dairy cows. Integration of DIM information into the prediction equation was found to be a good strategy to obtain biologically meaningful CH4 values from lactating cows by accounting for biological changes that occur throughout the lactation. PMID:26026761
Emission and Excitation Spectra of ZnO:Ga and ZnO:Ga,N Ceramics
Rodnyi, P A; Gorokhova, E I; Mikhrin, S B; Dorenbos, P
The spectral characteristics of ZnO:Ga and ZnO:Ga,N ceramics prepared by uniaxial hot pressing have been investigated. At room temperature, the edge (exciton) band at 3.12 eV dominates in the luminescence spectra of ZnO:Ga, while a wide luminescence band at 2.37 eV, which is likely to be due to zinc vacancies, is observed in the spectra of ZnO:Ga,N. Upon heating, the edge band maximum shifts to lower energies and the bandwidth increases. The extrapolated position of the edge-band maximum at zero temperature, Em(0) = 3.367 � 0.005 eV, is in agreement with the data for thin zinc oxide films. The luminescence excitation spectra in the range from 3 to 6.5 eV are reported and the mechanism of energy transfer to excitons and luminescence centers is considered.
X-ray emission spectra and gaps of CuFeO2 with the modified Becke-Johnson potential
NASA Astrophysics Data System (ADS)
Guo, San-Dong
We investigate the electronic structures of CuFeO2 by using Tran and Blaha's modified Becke and Johnson exchange potential. The calculated X-ray emission spectra of CuFeO2 for O-K and Fe-L are quite compatible with experimental data. The calculated energy band gap and optical band gap are 0.15 eV and 1.03 eV, respectively, and the theoretical magnetic moment for Fe atom is 4.11?B, which is very close to experimental value 4.2 � 0.1?B.
The similar emission-line spectra of the young star LkH-alpha 101 and the hypergiant MWC 300
NASA Astrophysics Data System (ADS)
Hamann, Fred; Persson, S. E.
High-resolution spectra from 0.63 to 1.75 microns are presented, showing that the luminous young star LkH-alpha 101 and the post-main-sequence hypergiant MWC 300 have very similar emission-line properties. Tables are given of line measurements and identifications. It is found that, in spite of their different histories, these stars have similar conditions of density, temperature, kinematics, and possibly geometry in their line-emitting envelopes. The results support models of hypergiants and luminous young stars which both invoke dense equatorial disks and suggest that disk structures around some evolved hot young stars are created by dense equatorial winds.
Luminescence emission and excitation spectra of benzene thin film under slow electron impact at 77 K
Hiraoka, K.; Nara, M.; Iijima, Y.
Luminescence bands of thin-film benzene at 77K, excited by slow electron impact, are attributed to fluorescence of the monomer at 280 nm, and tentatively to fluorescence and phosphorescence of benzene isomers at 303 and 395 nm, respectively. The electron impact excitation spectra dL/dV/sub i/ vs. eV/sub i/ for the 280-nm band were measured, where L is the luminescence intensity and eV/sub i/ is the electron energy. Four peaks are clearly resolved which served for the calibration of electron energy, and thus for the assignment of peaks in the electron transmission spectra. 2 figures.
Kawamuro, Taiki; Ueda, Yoshihiro; Tazaki, Fumie [Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan); Terashima, Yuichi [Department of Physics, Ehime University, Matsuyama 790-8577 (Japan)
We report the first broadband X-ray spectra of the low-luminosity active galactic nuclei (LLAGNs), NGC 1566 (type 1.5) and NGC 4941 (type 2), observed with Suzaku and Swift/BAT covering the 0.5-195 keV band. Both targets have hard X-ray luminosities of {approx}10{sup 41-42} erg s{sup -1} in the 15-55 keV band. The spectra of the nucleus are well reproduced by a sum of partially or fully covered transmitted emission and its reflection from the accretion disk, reprocessed emission from the torus accompanied by a strong narrow iron-K{alpha} line, and a scattered component (for NGC 4941). We do not significantly detect a broad iron-K{alpha} line from the inner accretion disk in both targets, and obtain an upper limit on the corresponding solid angle of {Omega}/2{pi} < 0.3 in NGC 1566. The reflection strength from the torus is moderate, {Omega}/2{pi}=0.45{sup +0.13}{sub -0.10} in NGC 1566 and {Omega}/2{pi}=0.64{sup +0.69}{sub -0.27} in NGC 4941. Comparison of the equivalent width of the narrow iron-K{alpha} line with a model prediction based on a simple torus geometry constrains its half-opening angle to be {theta}{sub oa} {approx_equal} 60 Degree-Sign -70 Degree-Sign in NGC 4941. These results agree with the obscured AGN fraction obtained from hard X-ray and mid-infrared selected samples at similar luminosities. Our results support the implication that the averaged covering fraction of AGN tori is peaked at L {approx} 10{sup 42-43} erg s{sup -1} but decreases toward lower luminosities.
L{beta}1 and L{beta}2 Satellites in the X-ray Emission Spectra
Poonia, Surendra [Division of Natural Resources and Environment, Central Arid Zone Research Institute, Jodhpur - 342 003, Rajasthan (India)
The X-ray satellites L{beta}{sub 1}{sup I}, L{beta}{sub 1}{sup II}, L{beta}{sub 1}{sup III}, L{beta}{sub 1}{sup IV}, L{beta}{sub 2}{sup I}, L{beta}{sub 2}{sup (b)}, L{beta}{sub 2}{sup II} and L{beta}{sub 2}{sup (c)} observed in the L-emission spectra in elements with Z = 26 to 92, have been calculated. The energies of various transitions have been calculated by available Hartree-Fock-Slater (HFS) data using the semi-empirical Auger transition energies in the doubly ionized atoms and their relative intensities have been estimated by considering cross - sections of singly ionized 2x-1 (x {identical_to} s, p) states and then of subsequent Coster-Kronig and shake off processes. The calculated spectra have been compared with the measured satellite energies in the L emission spectra. Their intense peaks have been identified as the observed satellite lines. The one to one correspondence between the peaks in calculated spectra and the satellites in measured spectra has been established on the basis of the agreement between the separations in the peak energies and those in the measured satellite energies. Group of transitions under the transition schemes L2Mx-MxM4,5 and L3Mx-MxN4,5 (x {identical_to} 1-5), which give rise to these satellites have been identified. It is observed that the satellite L{beta}{sub 2}{sup (b)} in all these spectra can be assigned to the superposition of 3F4-3G5 and 3F4-3D3 transitions and that this must be most intense one out of all these satellites, contributing in order of decreasing intensity. Each of the remaining satellites is found to have different origin in different elements. The possible contributions of the suitable transitions to all these lines have also been discussed.
Ion emission spectra in the Jovian X-ray aurora V. Kharchenko,1
Stancil, Phillip C.
, and distinct spectral features were detected. The bremsstrah- lung mechanism is not capable of explaining a reconciliation of the two spectral data sets and the inferred initial energies are consistent with the view-rays are characterized by two distinct components, which differ in morphology and in spectra. Two independent sources
A new non-LTE retrieval method for atmospheric parameters from mipas-envisat emission spectra
B. Funke; M. L�pez-Puertas; G. Stiller; T. V. Clarmann; M. H�pfner
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a high-resolution limb sounder on board the European polar platform ENVISAT, scheduled to be launched in 2001. A large number of atmospheric trace gases relevant to stratospheric ozone chemistry and global change are expected to be retrieved from the IR spectra covering a wide spectral range. While operational data analysis under
An Analysis of the Spectra of Three SEYFERT1 Galaxies with Strong CAII Emission
E. van Groningen
High resolution spectroscopy is presented of three Seyfert-1 galaxies - I Zw 1, Akn 564 and Mkn 231. The spectra cover the optical wavelength region and the regions with the Ca II triplet and the [Ca II] lines. The broad lines in I Zw 1 and Akn 564 are relatively narrow (FWHM < 1000 km s^-1^), and it is found
Analysis of emission spectra of Ho{sup 3+}:LFBCd glasses
Naresh, V., E-mail: firstname.lastname@example.com; Buddhudu, S., E-mail: firstname.lastname@example.com [Department of Physics, Sri Venkateswara University, Tirupati-517502 (India)
In the present paper, we report on the absorption and emission properties of (0.1-1.5 mol %) Ho{sup 3+} doped LFBCd (Li{sub 2}O{sub ?}LiF{sub ?}B{sub 2}O{sub 3?}CdO) glasses prepared via melt quenching method. On exciting these glasses at (?{sub exci}) = 452 nm, two emissions at 556 nm ({sup 5}S{sub 2}?{sup 5}I{sub 8}; Green), 655 nm ({sup 5}F{sub 5}?{sup 5}I{sub 8}; Red) have been obtained. Upon exciting these glasses with a 980 nm diode laser, NIR emissions at 1195 nm ({sup 5}I{sub 6}?{sup 5}I{sub 8}), 1951 nm ({sup 5}I{sub 7}?{sup 5}I{sub 8}) have been measured for 1 mol % Ho{sup 3+}:LFBCd glass. For higher concentration beyond 1.0 mol %, emission quenching of Ho{sup 3+} glass has been noticed and which has successfully been explained in terms of an energy level diagram. From absorption cross-section data, stimulated emission cross-section has been evaluated by applying McCumber's theory and further cross-sectional gain has also been computed for the emissions at 1195 nm (?1.20 ?m) and 1951 nm (?2.0 ?m) of 1 mol % Ho{sup 3+}:LFBCd glass.
Taking the spectral overlap between excitation and emission spectra of fluorescent materials into account with Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Leyre, Sven; Ryckaert, Jana; Acuna, Paula; Audenaert, Jan; Meuret, Youri; Hofkens, Johan; Durinck, Guy; Deconinck, Geert; Hanselaer, Peter
Monte Carlo ray tracing is an important simulation tool in applications where fluorescence is present, e.g. in bio-medical applications and in the design of luminaires and luminescent solar concentrators. A frequently used ray tracing procedure for fluorescence is the `dual stage' approach. In this approach, first, all sources are traced through the system and the rays absorbed in the fluorescent components are stored. Next, the emission from the fluorescent components is traced. This approach does not allow for subsequent re-absorption and re-emission effects in fluorescent materials with a spectral overlap between excitation and emission spectra. In this work, a `multi stage' ray tracing procedure for the simulation of luminescence is presented. Herein, wavelengths are traced from short to long separately and no distinction is made regarding the origin of emission (either a fluorescent component or a source). The presented approach can be easily implemented in existing commercial ray tracing software thus reducing the programming efforts for the new ray tracing algorithm and taking advantage of the strength of the selected ray tracing package concerning the modelling of complex geometrical systems. Both techniques are compared to investigate the influence of the selected ray tracing approach on the efficiency and colour prediction of a remote phosphor LED module.
Measurements of emission spectra from hot, dense germanium plasma in short pulse laser experiments
NASA Astrophysics Data System (ADS)
Hoarty, D. J.; James, S. F.; Brown, C. R. D.; Williams, B. M.; Chung, H. K.; Harris, J. W. O.; Upcraft, L.; Crowley, B. J. B.; Smith, C. C.; Lee, R. W.
Heating of thin foil targets by an high power laser at intensities of 10 17-10 19 W/cm 2 has been studied as a method for producing high temperature, high density samples to investigate X-ray opacity and equation of state. The targets were plastic (parylene-N) foils with a microdot made of a mixture of germanium and titanium buried at depth of 1.5 ?m. The L-shell spectra from the germanium and the K-shell spectra from the titanium were taken using crystal spectrometers recording onto film and an ultra fast X-ray streak camera coupled to a conical focussing crystal with a time resolution of 1 ps. The conditions in the microdot were inferred by comparing the measured spectra to synthetic spectra produced by the time-dependent collisional-radiative (CR) models FLY and FLYCHK. The data were also compared to simulated spectra from a number of opacity codes assuming local thermodynamic equilibrium (LTE). Temperature and density gradients were taken into account in the comparisons. The sample conditions were inferred from the CR modelling using FLYCHK to be 800 � 100 eV and 1.5 � 0.5 g/cc. The best fit to the LTE models was at a temperature 20% lower than with the CR model. Though the sample departs from LTE significantly useful spectral comparisons can still be made. The results and comparisons are discussed along with improvements to the experimental technique to achieve conditions closer to LTE.
Qualities related to spectra acquisition in inductively coupled plasma-atomic emission spectrometry
J.-M. Mermet
As many elements emit line-rich spectra in ICP-AES, the role of the resolution of the dispersive system has been considered as crucial not only to minimize spectral interferences but also to improve signal-to-background ratios. Resolution is mainly based on the line width measured at half of the peak intensity. Because of the availability of modern gratings, the practical resolution is
Photoluminescence emissions both in the visible and infrared spectra from thin, uncapped InN deposits
NASA Astrophysics Data System (ADS)
Laboutin, O. A.; Welser, R. E.
Thin, uncapped InN deposits on GaN buffer layers are grown and subsequently annealed in a metal organic chemical vapor deposition reactor. Atomic force microscopy imaging of the InN surface reveals a sudden transition from a two- to a three-dimensional structure with increasing growth time. Strong room-temperature photoluminescence is observed from the InN, with peak emissions in the 2.2-3.1 eV and 0.7-0.9 eV ranges. High-energy emissions are shown to be associated with a two-dimensional InN wetting layer, red shifting with increasing growth time and blue shifting with increasing annealing time. Low-energy emissions near the purported bulk energy gap of InN emerge in deposits with well-developed three-dimensional islands, but disappear when these islands are removed during the process of annealing.
Broadband Emission Spectra from the Cygnus X-3 Jet in the Soft Spectral State
NASA Astrophysics Data System (ADS)
Zhang, Jian-Fu; Lu, Ju-Fu
In order to understand the main observational characteristics of the Galactic X-ray binary Cygnus X-3, we propose a radiation model in which high-energy electrons accelerate in the dissipation zone of a jet and produce nonthermal broadband emissions. Broadband spectral energy distributions are computed to compare the AGILE and Fermi LAT data with the multi-band data during soft X-ray spectral states. By fitting observations at different locations of the jet, we find that the emission region is rather compact and should be located at a distance of about one orbital radius. Our results can explain the current multi-frequency observations and also predict the TeV band emission. The model could be tested by a polarization measurement at IR band, and/or by a correlation study between the GeV and TeV bands once very-high-energy observations are available.
Band-structure effects in photoelectron-emission spectra from metal surfaces
NASA Astrophysics Data System (ADS)
Rios Rubiano, C. A.; Gravielle, M. S.; Mitnik, D. M.; Silkin, V. M.
Photoelectron emission from the valence band of a metal surface due to the grazing incidence of ultrashort laser pulses is studied in the framework of a distorted-wave formulation. We propose a model, named the band-structure-based-Volkov (BSB-V) approximation, which takes into account the contribution of the band structure of the solid. The BSB-V approach is applied to calculate differential electron-emission probabilities for Al(111) and Be(0001) surfaces. A noticeable influence of the electronic band structure was observed in the case of beryllium, while for aluminum such effects were found to play a minor role.
The nature of the 2.8-micron emission feature in cometary spectra
NASA Astrophysics Data System (ADS)
Bockelee-Morvan, D.; Crovisier, J.
It is suggested that the the emission at 2.8 microns previously observed in the P/Halley 1986 III and Wilson 1987 VII comets is mainly due to the long-wavelength parts of the nu and (101-100) water bands. Much weaker contributions come from other water bands and from vibrationaly excited OH produced by H2O photolysis. Synthetic profiles of these emissions are presented and compared to the observations. The water production rates of the comets are derived.
Energy deposition spectra of simultaneous electron emissions from low energy protons�
DePriest, Kendall Russell
an electron is known as charge exchange. DuBois has made extensive measurements of doubly differential cross-sections for ion/atom collisions and has attempted to measure multiple electron emission cross-sections (DuBois and Manson 1990; Toburen and Du...Bois 1994; Manson and DuBois 1992). Recently, DuBois (1998) suggests that the fraction of charge exchange events that result in the simultaneous emission of electrons may be larger than previously assumed. An increased number of these electrons may...
Experimental study on the emission spectra of microwave plasma at atmospheric pressure
Zhang, Boya; Wang, Qiang; Zhang, Guixin, E-mail: firstname.lastname@example.com [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Shanshan [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Shenzhen Power Supply Co. Ltd., Shenzhen 518000, Guangdong (China)
An experimental study on microwave plasma at atmospheric pressure was conducted by employing optical emission spectroscopy. Based on a microwave plasma generation device developed for nanoparticle synthesis, we studied the influence of input microwave power and gas flow rate on the optical emission behaviors and electron temperature of plasma using Ar, He, and N{sub 2} as working gas, respectively. The physics behind these behaviors was discussed. The results are useful in characterizing microwave plasma at atmospheric pressure and can be used for improving nanoparticle synthesis system for commercial use in the future.
Modeling of Optical Emission Spectra in an Ar Pulsed Discharge to Determine Absolute Metastable Density
S. F. Adams; J. A. Miles; A. C. Laber; J. M. Williamson
Optical emission measurements of relative intensities of violet spectral lines in an Ar pulsed discharge have been combined with available electron-impact cross sections to yield absolute Ar metastable species concentration. An enabling factor of this analysis is that the electron excitation pattern from the Ar singlet ground state and the triplet metastable state (1s in Paschen's notation) is quite different
The Characteristics of Millisecond Pulsar Emission. I. Spectra, Pulse Shapes, and the Beaming Fraction
Michael Kramer; Kiriaki M. Xilouris; Duncan R. Lorimer; Oleg Doroshenko; Axel Jessner; Richard Wielebinski; Alexander Wolszczan; Fernando Camilo
The extreme physical conditions in millisecond pulsar magnetospheres, as well as an evolutionary history that differs from that of normal pulsars, raise the question whether these objects also differ in their radio emission properties. We have monitored a large sample of millisecond pulsars for a period of 3 yr using the 100 m Effelsberg radio telescope in order to compare
Technology Transfer Automated Retrieval System (TEKTRAN)
Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll fluorescence (Chlorophyll fluorescence) peaks centered at 685"10 nm and 735"5 nm. Methods ha...
Vibrational and rotational analysis of the emission spectra of the arc jet flow
NASA Technical Reports Server (NTRS)
Blount, Charles E.
Applying atomic and molecular physics to the analysis of the radiation emitted from the arc jet flow provides a means for determining the species and excitation temperature of the constituents of the flow. A rotational and vibrational analysis of the spectra obtained from the radiation emitted in the shock layer and in the free stream of the jet flow was performed, specifically, in the shock layer bands of the First Negative Group of ionized molecular nitrogen and in the free stream of the gamma-system of nitric oxide.
Rigorous Franck�Condon absorption and emission spectra of conjugated oligomers from quantum chemistry
Stoyan Karabunarliev; Martin Baumgarten; Eric R. Bittner
A harmonic Condon approach is used to calculate excitation and emission band shapes for the lowest dipole-allowed electronic transitions in conjugated oligomers: polyenes, oligorylenes, and para-phenylenevinylenes. Ground- and excited-state adiabatic energies, equilibrium structures, and vibrational modes are obtained within standard all-valence-electron molecular Hamiltonian incorporating extended configuration interaction. The interstate distortion is cast in normal coordinates and used to calculate transition
Rigorous Franck-Condon absorption and emission spectra of conjugated oligomers from quantum chemistry
Stoyan Karabunarliev; Martin Baumgarten; Eric R. Bittner; Klaus M�llen
A harmonic Condon approach is used to calculate excitation and emission band shapes for the lowest dipole-allowed electronic transitions in conjugated oligomers: polyenes, oligorylenes, and para-phenylenevinylenes. Ground- and excited-state adiabatic energies, equilibrium structures, and vibrational modes are obtained within standard all-valence-electron molecular Hamiltonian incorporating extended configuration interaction. The interstate distortion is cast in normal coordinates and used to calculate transition
Circumstellar molecular line absorption and emission in the optical spectra of post-AGB stars
Eric J. Bakker; Henny J. G. L. M. Lamers; L. B. F. M. Waters; Ton Schoenmaker
We present a list of post-AGB stars showing molecular line absorption and emission in the optical spectrum. Two objects show CH+, one in emission and one in absorption, and ten stars show C2 and CN in absorption. The Doppler velocities of the C2 lines and the rotational temperatures indicate that the line forming region is the AGB remnant. An analysis of the post-AGB stars of which CO millimeter data is available suggests that the C2} expansion velocity is of the same order as the CO expansion velocity. HD56126 has been studied in detail and we find a mass-loss rate of Mdot=2.8e-4 Msol/yr, fC2=2.4e-8 and fCN=1.3e-8. The mass loss derived from C2 is significantly larger than Mdot=1.2e-5 Msol/yr derived from CO. We find that all objects with the 21mu feature in emission show C2 and CN absorption, but not all objects with C2 and CN detections show a 21mu feature.
1er cru: A spectropolarimeter to measure the polarisation of auroral thermospheric emission spectra
NASA Astrophysics Data System (ADS)
Barthelemy, Mathieu; Lamy, Herve; Lilensten, Jean; Vialatte, Anne
The polarisation of auroral thermospheric red line have been detected few years ago with degree of polarisation around 2% (Lilensten et al. 2008). Since then several measurements campaign and simulation have been performed (Barthelemy et al. 2011, Lilensten et al. 2013). However, the polarisation of other lines have never been explored. We built a spectropolarimeter able to cover the auroral spectrum from 400 nm to 700 nm with spectral resolution down to 0.5 nm. The first light of the instrument have been performed in December 2014 in Skibotn (Norway). Despite some misalignments problem, we have been able to get some spectra on both ordinary and extraordinary channels. The data are underprocessing but we are confident to be able to extract the polarisation of some other lines. We will especially check that the green line is unpolarized as explained in Bommier et al. (2011).
Fluorescence excitation-emission matrix spectra coupled with parallel factor and regional integration analysis to characterize organic matter humification.
He, Xiao-Song; Xi, Bei-Dou; Li, Xiang; Pan, Hong-Wei; An, Da; Bai, Shuo-Guo; Li, Dan; Cui, Dong-Yu
The present several humification indexes cannot provide the whole fluorescence information on organic matter composition and the evaluation results from them are inconsistent sometimes. In this study, fluorescence excitation-emission matrix spectra coupled with parallel factor analysis and fluorescence regional integration analysis were utilized to investigate organic matter humification, and the projection pursuit cluster (PPC) model was applied to form a suitable index for overcoming the difficulties in multi-index evaluation. The result showed that the ratio between the volume of humic- and fulvic-like fluorescence region and the volume of protein-like fluorescence region not only revealed the heterogeneity of organic matter, but also provided more accurate information on organic matter humification. In addition, the results showed that the PPC model could be used to characterize integrally the humification, and the projected characteristic value calculated from the PPC model could be used as the integrated humification evaluation index. PMID:23706894
Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.
Keenan, F P; Aller, L H; Ryans, R S; Hyung, S
Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676
Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae
Keenan, Francis P.; Aller, Lawrence H.; Ryans, Robert S. I.; Hyung, Siek
Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d6 levels of Fe III and among the 3d2 levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures Te = 7,000�20,000 K and densities Ne = 102-108 cm?3, whereas those for [Fe VII] are provided for Te = 10,000�30,000 K and Ne = 102-108 cm?3. The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676
Infrared and near infrared emission spectra of SbH and SbD
NASA Astrophysics Data System (ADS)
Yu, Shanshan; Fu, Dejian; Shayesteh, Alireza; Gordon, Iouli E.; Appadoo, Dominique R. T.; Bernath, Peter
The X3? - ground state vibration-rotation spectrum of SbH and the near infrared spectra of the b1? +- X3? - transitions of SbH and SbD have been measured at high resolution by Fourier transform spectroscopy. The SbH and SbD radicals were generated in a tube furnace with a D.C. discharge of a flowing mixture of argon, hydrogen (or deuterium), and antimony vapor. In the infrared region, the 1-0 and 2-1 bands of the three components (0 +, 1 e, and 1 f) as well as the 0 + component of the 3-2 band were observed for 121SbH and 123SbH. In the near infrared region, the 0-0, 1-1, and 2-2 bands of the b1? +- X3? - system of both SbH and SbD as well as the 3-3 band of SbD were observed. Except for a few lines, the antimony isotopic shift was not resolved for these electronic spectra. The present data set was combined with the available ground state data on SbD and a1? data for SbH and SbD from previous work, and a least-squares fit was performed for each of the four isotopologues: 121SbH, 123SbH, 121SbD, and 123SbD. Improved spectroscopic constants were obtained for the observed vibrational levels of the X3? -, a1?, and b1? + states of these four isotopologues. In addition, all the above data were also fitted simultaneously to a multi-isotopologue Dunham model, which yielded Dunham constants and Born-Oppenheimer breakdown parameters for these three electronic states. Interestingly, we found that Born-Oppenheimer breakdown corrections were also required for some of the spin-spin and spin-rotation parameters of the X3? - state.
Using violet laser-induced chlorophyll fluorescence emission spectra for crop yield assessment of cowpea (Vigna unguiculata (L) Walp) varieties
NASA Astrophysics Data System (ADS)
Anderson, Benjamin; Buah-Bassuah, Paul K.; Tetteh, Jonathan P.
The use of violet laser-induced chlorophyll fluorescence (LICF) emission spectra to monitor the growth of five varieties of cowpea in the University of Cape Coast Botanical Garden is presented. Radiation from a continuous-wave violet laser diode emitting at 396 nm through a fibre is closely incident on in vivo leaves of cowpea to excite chlorophyll fluorescence, which is detected by an integrated spectrometer with CCD readout. The chlorophyll fluorescence spectra with peaks at 683 and 731 nm were used for growth monitoring of the cowpea plants over three weeks and analysed using Gaussian spectral functions with curve fitted parameters to determine the peak positions, area under the spectral curve and the intensity ratio F683/F731. The variation in the intensity ratio of the chlorophyll bands showed sensitive changes indicating the photosynthetic activity of the cowpea varieties. A discussion of the fluorescence result as compared to conventional assessment is presented with regard to discrimination between the cowpea varieties in terms of crop yield performance.
Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths
NASA Astrophysics Data System (ADS)
Ito, Yuichi; Ikoma, Masahiro; Kawahara, Hajime; Nagahara, Hiroko; Kawashima, Yui; Nakamoto, Taishi
Motivated by recent detection of transiting high-density super-Earths, we explore the detectability of hot rocky super-Earths orbiting very close to their host stars. In an environment hot enough for their rocky surfaces to be molten, they would have an atmosphere composed of gas species from the magma oceans. In this study, we investigate the radiative properties of the atmosphere that is in gas/melt equilibrium with the underlying magma ocean. Our equilibrium calculations yield Na, K, Fe, Si, SiO, O, and O2 as the major atmospheric species. We compile the radiative absorption line data of those species available in the literature and calculate their absorption opacities in the wavelength region of 0.1-100 ?m. Using them, we integrate the thermal structure of the atmosphere. Then, we find that thermal inversion occurs in the atmosphere because of the UV absorption by SiO. In addition, we calculate the ratio of the planetary to stellar emission fluxes during secondary eclipse, and we find prominent emission features induced by SiO at 4 ?m detectable by Spitzer, and those at 10 and 100 ?m detectable by near-future space telescopes.
Fluorescence excitation and emission spectra of ALA-induced protoporphyrin IX in normal and tumoral tissue of the human bladder
NASA Astrophysics Data System (ADS)
Forrer, Martin; Glanzmann, Thomas M.; Mizeret, Jerome C.; Braichotte, Daniel; Wagnieres, Georges A.; van den Bergh, Hubert; Jichlinski, Patrice; Leisinger, Hans-Juerg
In vivo spectrofluorometric analysis represents a tool to obtain information about fluorophore distribution in tissue. Based on a Peltier-cooled CCD we designed a fluorescence excitation and emission spectrograph which allows to obtain tissue spectra endoscopically and in a clinical environment. Clinical studies were performed on patients with positive cytology or tumor recurrence in the urinary bladder. Patients received a 50 ml instillation of 3% ALA solution at pH 5.5 during 3 to 4 hours and underwent a normal white light cystoscopic examination together with light induced fluorescence photodetection at 5 to 8 hours after the beginning of the instillation. Local fluorescence measurements with a single fiber were performed before photodetection. These showed fluorescence ratios between tumor and normal tissue of 1.5 to 20 with the strongest ratios for exophytic papillary tumors. Fluorescence excitation between 380 nm and 450 nm revealed that the higher Protoporphyrin IX (PPIX) signal on tumor tissue is accompanied by a decrease of the autofluorescence at the emission wavelength of 500 nm.
Emission and absorption of photons and the black-body spectra in Lorentz-odd Electrodynamics
J. M. Fonseca; A. H. Gomes; W. A. Moura-Melo
We study a number of issues related to the emission and absorption radiation by non-relativistic electrons within the framework of a Lorentz-breaking electrodynamics in (3+1) dimensions. Our main results concern how Planck-like spectrum law is sensitive to terms that violate Lorentz symmetry. We have realized that Planck law acquires extra terms proportional to the violating parameters: for the CPT-odd model, the leading extra terms appear to be linear or quadratic in these violating parameters according to the background vector is parallel or perpendicular to the photon wave-vector. In the CPT-even case a linear `correction' shows up. Among other possible ways to probe for these violations, by means of the present results, we may quote the direct observation of the extra contributions or an unbalancing in the mean occupation number of photon modes in a given thermal bath.
Ion temperatures in HIP-1 and SUMMA from charge-exchange neutral optical emission spectra
NASA Technical Reports Server (NTRS)
Patch, R. W.; Lauver, M. R.
Ion temperatures were obtained from observations of the H sub alpha, D sub alpha, and He 587.6 nm lines emitted from hydrogen, deuterium, and helium plasmas in the SUMMA and HIP-1 mirror devices at Lewis Research Center. Steady state discharges were formed by applying a radially inward dc electric field between cylindrical or annular anodes and hollow cathodes located at the peaks of the mirrors. The ion temperatures were found from the Doppler broadening of the charge-exchange components of spectral lines. A statistical method was developed for obtaining scaling relations of ion temperature as a function of current, voltage, and magnetic flux density. Derivations are given that take into account triangular monochromator slit functions, loss cones, and superimposed charge-exchange processes. In addition, the Doppler broadening was found to be sensitive to the influence of drift on charge-exchange cross section. The effects of finite ion-cyclotron radius, cascading, and delayed emission are reviewed.
Stratospheric minor constituent distributions from far-infrared thermal emission spectra
NASA Technical Reports Server (NTRS)
Abbas, Mian M.; Traub, Wesley A.
We retrieve mixing ratio profiles of O3, H2(O-16), H2(O-17), H2(O-18), HF, and HCl from far-infrared thermal emission observations of the limb in the 80-220 cm/sec spectral region. The observations were made with a balloon-borne Fourier transform spectrometer as a part of the 1983 Balloon Intercomparison Campaign (BIC-2). A subset of the data was analyzed previously using the method in the work of Traub et al. (1982, 1991); in the present paper we use an alternative method of calibration and analysis, given by Abbas et al. (1985). The retrieved constituent profiles are compared with the measurements made with other instruments on the BIC-2 flights. The results for the concentrations of H2(O-17) and H2(O-18) obtained in this study indicate no isotopic enhancement or depletion with a standard deviation of about 20 percent.
The nebular spectra of SN 2012aw and constraints on stellar nucleosynthesis from oxygen emission lines
Jerkstrand, A; Fraser, M; Fransson, C; Sollerman, J; Taddia, F; Kotak, R
We present nebular phase optical and near-infrared spectroscopy of the Type IIP supernova SN 2012aw combined with NLTE radiative transfer calculations applied to ejecta from stellar evolution/explosion models. Our spectral synthesis models generally show good agreement with the ejecta from a MZAMS = 15 Msun progenitor star. The emission lines of oxygen, sodium, and magnesium are all consistent with the nucleosynthesis in a progenitor in the 14 - 18 Msun range. We also demonstrate how the evolution of the oxygen cooling lines of [O I] 5577 A, [O I] 6300 A, and [O I] 6364 A can be used to constrain the mass of oxygen in the non-molecularly cooled ashes to 20 Msun progenitor.
Improved fluorescence excitation-emission matrix regional integration to quantify spectra for fluorescent dissolved organic matter.
Zhou, Jie; Wang, Jun-Jian; Baudon, Antoine; Chow, Alex T
The purpose of this short communication is to demonstrate the importance of numerical analysis and wavelength increment selection when characterizing fluorescent dissolved organic matter (FDOM) using fluorescence excitation-emission matrix (EEM) regional integration. A variety of water samples, representing a landscape gradient and different types of FDOM, were analyzed for their percentage distribution of five operationally defined FDOM fractions (aromatic protein I, aromatic protein II, fulvic acid-like, soluble microbial byproduct-like, and humic acid-like) using three numerical methods in integrating volume under the surface of the fluorescence EEMs: Riemann summation, composite trapezoidal rule, and composite Simpson's rule. The influence of wavelength increment was also examined for the precision of the percentage distribution of each fraction. Our results show that the FDOM fraction estimated by Riemann summation with a 10- or 5-nm excitation wavelength can cause >40% or >5% errors, respectively, when compared with the best estimated values obtained by averaging results from composite trapezoidal rule and composite Simpson's rule with 1-nm excitation wavelength at the same emission increment. Also, our experiments show that fluorescence matrix regional integration could underestimate the two aromatic protein fractions but could overestimate the soluble microbial byproduct-like and humic acid-like fractions if improper increment and integral methods are used. The error can be reduced if a smaller wavelength increment is used. The smallest increment in a spectrofluorometer and composite Simpson's rule should be used for scanning fluorescence EEMs and calculating the percentage distribution of each FDOM fraction. Alternatively, 5-nm wavelength increments with composite Simpson's rule could be cost effective, and the error of each FDOM fraction commonly falls within 5% compared with those estimated by 1-nm increments. PMID:23673961
The effect of high temperatures on the mid-to-far-infrared emission and near-infrared reflectance spectra of phyllosilicates and natural
Glotch, Timothy D.
The effect of high temperatures on the mid-to-far-infrared emission and near-infrared reflectance altered or melted. We characterized the effects of high temperatures on the mid-to-far-infrared (mid-to-far-IR) emission (100�1400 cm�1 ; 7.1�100 lm) and near-infrared (NIR) reflectance (1.2�2.5 lm) spectra
Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths
Ito, Yuichi; Kawahara, Hajime; Nagahara, Hiroko; Kawashima, Yui; Nakamoto, Taishi
Motivated by recent detection of transiting high-density super-Earths, we explore the detectability of hot rocky super-Earths orbiting very close to their host stars. In the environment hot enough for their rocky surfaces to be molten, they would have the atmosphere composed of gas species from the magma oceans. In this study, we investigate the radiative properties of the atmosphere that is in the gas/melt equilibrium with the underlying magma ocean. Our equilibrium calculations yield Na, K, Fe, Si, SiO, O, and O$_2$ as the major atmospheric species. We compile the radiative-absorption line data of those species available in literature, and calculate their absorption opacities in the wavelength region of 0.1--100~$\\mathrm{\\mu m}$. Using them, we integrate the thermal structure of the atmosphere. Then, we find that thermal inversion occurs in the atmosphere because of the UV absorption by SiO. In addition, we calculate the ratio of the planetary to stellar emission fluxes during secondary eclipse, and find pr...
Emission spectra from direct current and microwave powered Hg lamps at very high pressure
NASA Astrophysics Data System (ADS)
Hamady, M.; Lister, G. G.; Stafford, L.
Discharge lamps containing mercury at pressures above 100 bar are commercially used in data projectors and television projector systems. Due to their small size, these lamps are difficult to investigate experimentally, but spectral measurements, combined with radiation transport calculations, have provided useful information on the visible spectrum. However, classical spectral line broadening theory is inadequate to describe the UV portion of the spectrum, so self-consistent modelling of these discharges is not possible at present. This paper discusses the differences between discharges containing electrodes and discharges sustained by a microwave (mw) electromagnetic field, on the basis of the experimentally measured temperature profile in an electroded discharge, and a temperature profile computed from a 1D power balance model for a microwave discharge. A model based on the ray-tracing method is employed to simulate the radiation transport in these lamps. The model has been validated by comparing the emission spectrum from dc discharge lamps with those obtained experimentally. The output flux, luminous flux, luminous efficacy, the correlated colour temperature, the chromaticity coordinates and photometric curves of the lamp were then obtained. These results were also compared with those of a theoretically calculated temperature profile for the same lamp, excited by microwave power in the TM010 mode.
Retrieval of stratospheric O3, HNO3, and ClONO2 profiles from 1992 MIPAS-B limb emission spectra: method, results, and error analysis
T. von Clarmann; H. Fischer; F. Friedl-Vallon; A. Linden; H. Oelhaf; C. Piesch; M. Seefeldner; W. V�lker
Within the framework of the European Arctic Stratospheric Ozone Experiment, two flights of the balloon-borne MIPAS-B limb emission spectrometer were performed in the Arctic stratosphere from Kiruna, northern Sweden. During the early hours of January 13 and the night from March 14 to March 15, 1992, several limb sequences of infrared spectra were recorded which have permitted the retrieval of
Characterization of tropical atmosphere through wide-band emission spectra acquired with a balloon-borne uncooled FTS spectroradiometer
NASA Astrophysics Data System (ADS)
Bianchini, Giovanni; Palchetti, Luca; Carli, Bruno; Cortesi, Ugo; Del Bianco, Samuele
On June 30th, 2005 the REFIR-PAD (Radiation Explorer in the Far InfraRed-Prototype for Application and Development) Fourier transform spectroradiometer performed the first wide-band spectral characterization of the top-of-atmosphere emitted radiation in the far-infrared with an uncooled instrument. The nadir emitted radiance has been measured down to 100 cm -1, thus covering a spectral interval that, until now, was nearly unexplored, and up to 1400 cm -1, including the well characterized atmospheric window region, in which it is possible to perform comparison and intercalibration with operative instruments. The measurements were performed at an altitude of 34 km, from a stratospheric balloon launched in tropical region, near Teresina, Brazil). The acquired spectra have a spectral resolution of 0.5 cm -1. It should be noted that despite the operating spectral range extending to the far-infrared region, REFIR-PAD does not require any cooled components, thanks to the use of pyroelectric detectors and an optical scheme that compensates for the instrument self-emission. This work shows the results of the analysis of the spectra, focusing on the far infrared portion of the atmospheric emitted radiance. The retrieval of the vertical profiles of water vapour and temperature during the flight is presented. The vertical resolution of the retrieval is 2 km in the upper troposphere-lower stratosphere (UTLS) region, and lower at higher altitudes. The comparison with ECMWF for validation is also shown. Besides the characterization of temperature and water vapour, from the analysis of the emitted radiance useful information can be gathered about cloud and aerosol contribution to radiation budget.
Demonstration of Successful X-ray Thomson Scattering Using Picosecond K-(alpha) X-ray Sources for the Characterization of Dense Heated Matter
Kritcher, A; Neumayer, P; Lee, H J; Doeppner, T; Falcone, R; Glenzer, S; Morse, E C
We discuss the first successful K-{alpha} x-ray Thomson scattering experiment from solid density plasmas for use as a diagnostic in determining the temperature, density, and ionization state of warm dense matter with picosecond resolution. The development of this source as a diagnostic and stringent requirements for successful K-{alpha} x-ray Thomson scattering are addressed. Data for the experimental techniques described in this paper [1] suggest the capability of single shot characterization of warm dense matter and the ability to use this scattering source at future Free Electron Lasers (FEL) where comparable scattering signal levels are predicted.
Redshifts of high-temperature emission lines in the far-ultraviolet spectra of late-type stars
NASA Technical Reports Server (NTRS)
Ayres, T. R.; Stencel, R. E.; Linsky, J. L.; Simon, T.; Jordan, C.; Brown, A.; Engvold, O.
High-dispersion IUE spectra of six late-type stars exhibit small but statistically significant differential redshifts of high-temperature emission lines, like Si IV and C IV, with respect to low-temperature lines like S I and O I. A well-exposed, small-aperture spectrum of the active chromosphere binary Capella (Alpha Aurigae A: G6 II+F9 III) establishes that the high-temperature lines are redshifted in an absolute sense with respect to the accurately determined photospheric velocity of the system at single-line phase 0.50. Several possible explanations for the stellar redshifts are discused, including a warm wind (100,000 K) in which aparent redshifts are produced in optically thick lines by an accelerating outfow, and the downflowing component of a vertical circulation system for which the up-leg portion of the flow is too cool, too hot, or too tenuous to be visible in Si IV and C IV. If the second scenario is true, the stellar redshifts may provide an important phenomenological link to the downflows observed in 100,000 K species over magnetic active regions in the sun.
Research as a guide for curriculum development: An example from introductory spectroscopy. I. Identifying student difficulties with atomic emission spectra
NASA Astrophysics Data System (ADS)
Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.
This is the first of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. This article (Paper I) describes how several serious conceptual and reasoning difficulties were identified among students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. Paper II illustrates how findings from this research informed the development of a tutorial that led to significant improvement in student understanding of atomic emission spectra.
Research as a guide for curriculum development: An example from introductory spectroscopy. II. Addressing student difficulties with atomic emission spectra
NASA Astrophysics Data System (ADS)
Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.
This is the second of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. Paper I describes how several conceptual and reasoning difficulties were identified among university students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. This second article (Paper II) illustrates how findings from this research informed the development of a tutorial that led to improvement in student understanding of atomic emission spectra.
Absolute Time-Resolved Emission of Non-LTE L-Shell Spectra from Ti-Doped Aerogels
Back,C.; Feldman, U.; Weaver, J.; Seely, J.; Constantin, C.; Holland, G.; Lee, R.; Chung, H.; Scott, H.
Outstanding discrepancies between data and calculations of laser-produced plasmas in recombination have been observed since the 1980s. Although improvements in hydrodynamic modeling may reduce the discrepancies, there are indications that non-LTE atomic kinetics may be the dominant cause. Experiments to investigate non-LTE effects were recently performed at the NIKE KrF laser on low-density Ti-doped aerogels. The laser irradiated a 2 mm diameter, cylindrical sample of various lengths with a 4-ns square pulse to create a volumetrically heated plasma. Ti L-shell spectra spanning a range of 0.47-3 keV were obtained with a transmission grating coupled to Si photodiodes. The diagnostic can be configured to provide 1-dimensional spatial resolution at a single photon energy, or 18 discrete energies with a resolving power, {gamma}/{delta}{gamma} of 3-20. The data are examined and compared to calculations to develop absolute emission measurements that can provide new tests of the non-LTE physics.
Absolute, time-resolved emission of non-LTE L-shell spectra from Ti-doped aerogels
NASA Astrophysics Data System (ADS)
Back, C. A.; Feldman, U.; Weaver, J. L.; Seely, J. F.; Constantin, C.; Holland, G.; Lee, R. W.; Chung, H.-K.; Scott, H. A.
Outstanding discrepancies between data and calculations of laser-produced plasmas in recombination have been observed since the 1980s. Although improvements in hydrodynamic modeling may reduce the discrepancies, there are indications that non-LTE atomic kinetics may be the dominant cause. Experiments to investigate non-LTE effects were recently performed at the NIKE KrF laser on low-density Ti-doped aerogels. The laser irradiated a 2 mm diameter, cylindrical sample of various lengths with a 4-ns square pulse to create a volumetrically heated plasma. Ti L-shell spectra spanning a range of 0.47 3 keV were obtained with a transmission grating coupled to Si photodiodes. The diagnostic can be configured to provide 1-dimensional spatial resolution at a single photon energy, or 18 discrete energies with a resolving power, ?/?? of 3 20. The data are examined and compared to calculations to develop absolute emission measurements that can provide new tests of the non-LTE physics.
Role of the charge transfer process in the formation of X-ray fluorescence and X-ray photoelectron spectra in copper (II) compounds
M. S. Osadchii; V. V. Murakhtanov; E. S. Fomin; L. N. Mazalov
A theoretical analysis of the Cu 1s and Cu 2p X-ray photoelectron spectra and CuK-alpha line in copper (II) compounds is performed within the framework of the Larsson model and the SCF-X-alpha-SW method. Both methods indicate independently the presence in the CuK-alpha spectrum of the intense shake-up satellite located about 0.4 eV from the main line in the LW region.
Complex Organic Matter in Space: About the Chemical Composition of Carriers of the Unidentified Infrared Bands (UIBs) and Protoplanetary Emission Spectra Recorded from Certain Astrophysical Objects
NASA Astrophysics Data System (ADS)
Cataldo, Franco; Keheyan, Yeghis; Heymann, Dieter
In this communication we present the basic concept that the pure PAHs (Polycyclic Aromatic Hydrocarbons) can be considered only the ideal carriers of the UIBs (Unidentified Infrared Bands), the emission spectra coming from a large variety of astronomical objects. Instead we have proposed that the carriers of UIBs and of protoplanetary nebulae (PPNe) emission spectra are much more complex molecular mixtures possessing also complex chemical structures comparable to certain petroleum fractions obtained from the petroleum refining processes. The demonstration of our proposal is based on the comparison between the emission spectra recorded from the protoplanetary nebulae (PPNe) IRAS 22272+ 5435 and the infrared absorption spectra of certain `heavy' petroleum fractions. It is shown that the best match with the reference spectrum is achieved by highly aromatic petroleum fractions. It is shown that the selected petroleum fractions used in the present study are able to match the band pattern of anthracite coal. Coal has been proposed previously as a model for the PPNe and UIBs but presents some drawbacks which could be overcome by adopting the petroleum fractions as model for PPNe and UIBs in place of coal. A brief discussion on the formation of the petroleum-like fractions in PPNe objects is included.
Complex organic matter in space: about the chemical composition of carriers of the Unidentified Infrared Bands (UIBs) and protoplanetary emission spectra recorded from certain astrophysical objects.
Cataldo, Franco; Keheyan, Yeghis; Heymann, Dieter
In this communication we present the basic concept that the pure PAHs (Polycyclic Aromatic Hydrocarbons) can be considered only the ideal carriers of the UIBs (Unidentified Infrared Bands), the emission spectra coming from a large variety of astronomical objects. Instead we have proposed that the carriers of UIBs and of protoplanetary nebulae (PPNe) emission spectra are much more complex molecular mixtures possessing also complex chemical structures comparable to certain petroleum fractions obtained from the petroleum refining processes. The demonstration of our proposal is based on the comparison between the emission spectra recorded from the protoplanetary nebulae (PPNe) IRAS 22272+ 5435 and the infrared absorption spectra of certain 'heavy' petroleum fractions. It is shown that the best match with the reference spectrum is achieved by highly aromatic petroleum fractions. It is shown that the selected petroleum fractions used in the present study are able to match the band pattern of anthracite coal. Coal has been proposed previously as a model for the PPNe and UIBs but presents some drawbacks which could be overcome by adopting the petroleum fractions as model for PPNe and UIBs in place of coal. A brief discussion on the formation of the petroleum-like fractions in PPNe objects is included. PMID:14979641
Complex X-ray Absorption and the Fe K(alpha) Profile in NGC 3516
NASA Technical Reports Server (NTRS)
Turner, T. J.; Kraemer, S. B.; George, I. M.; Reeves, J. N.; Botorff, M. C.
We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of approximately 1100 kilometers per second, has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (approximately 2.5 x 10(exp 23) per square centimeter) of highly ionized gas with a covering fraction approximately 50%. This low covering fraction suggests that the absorber lies within a few 1t-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the November dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.
The 21 micron emission band in the IRAS/LRS spectra of H II regions - Evidence of iron oxide in the interstellar medium
NASA Astrophysics Data System (ADS)
Cox, P.
The 21-micron emission line, recently found in four post-AGB stars by Kwok et al. (1989) is found to be ubiquitous in the IRAS/LRS midinfrared spectra of H II regions, accounting for about 20 percent of the total IRAS luminosity of these regions. Based on laboratory infrared absorption spectra, it is proposed that the carriers are iron oxides, such as maghemite (gamma-Fe2O3) or magnetite (Fe3O4). The magnetite found in the Orgueil meteorite provides the best spectroscopic match. The results support the Davis-Greenstein mechanism of the interstellar polarization.
Ultraviolet high-excitation Fe II fluorescence lines excited by O VI, C IV, and H I resonance emission as seen in IUE spectra
NASA Technical Reports Server (NTRS)
Feibelman, Walter A.; Bruhweiler, Frederick C.; Johansson, Sveneric
Archival high-dispersion spectra from the IUE are used in a search for Bowen emission lines of Fe II excited by the stronger transition of the O VI resonance doublet. The possibility of using these Fe II emission lines as a diagnostic of the strength of the far-ultraviolet emission of O VI at 1032 A is explored. It is found that the Fe II emission lines are quite common and strong in symbiotic stars, particularly those of the type known as 'symbiotic novae', as well as in normal novae. The lines are observed in central stars of some planetary nebulae of the O VI sequence besides a few central stars of type WR. High density, high excitation, and high temperature are suggested to be requirements for the excitation of the Fe II fluorescence lines. It is pointed out that while these lines were observed in PG 1159-035 and K1-16, they were not observed in AGNs.
Searching double-peaked emission-line profiles in the spectra of galaxies through the symmetry of the cross-correlation function
NASA Astrophysics Data System (ADS)
Garc�a-Lorenzo, B.
The presence of double-peaked/multi-component emission-line profiles in the spectra of galaxies is commonly identified by visual inspection. However, the identification of complex emission-line profiles by eye is unlikely for large data bases such as the Sloan Digital Sky Survey (SDSS) or the integral field spectroscopy surveys of galaxies (e.g. Calar Alto Legacy Integral Field Area Survey or The Mapping Nearby Galaxies at APO). We describe a quick method involving a cross-correlation technique for detecting the presence of complex (double-peaked or multiple components) profiles in the spectra of galaxies, deriving simultaneously a first estimation of the velocity dispersions and radial velocities of the dominant gaseous component. We illustrate the proposed procedure with the well-known complex [O III]??4959, 5007 profiles of the central region of NGC 1068.
Solvent effect on UV/Vis absorption and emission spectra in aqueous solution based on a modified form of solvent reorganization energy
NASA Astrophysics Data System (ADS)
Ren, HaiSheng; Ming, MeiJun; Zhu, Jun; Ma, JianYi; Li, XiangYuan
In this Letter, novel form of solvatochromic shifts for absorption and emission spectra are proposed. As a typical test, the lowest transitions of s-trans-acrolein in aqueous solution are investigated. The obtained absorption solvent shift of 0.22 eV is in good agreement with the experimental value of 0.20 eV. In addition, we predict emission solvent shift of -0.16 eV. This value seems more reasonable comparing with the value of -0.12 eV by the traditional theory. The contributions to the shift are discussed and electrostatic polarization components are found to be crucial for electronic spectra of acrolein in water.
Effect of atomic magnetic moments on the relative intensity of the L ? and L ? components in x-ray emission spectra of 3 d transition metal oxides
V. I. Grebennikov; V. R. Galakhov; L. D. Finkel�shtein; N. A. Ovechkina; �. Z. Kurmaev
The integrated-intensity ratio R of the L\\u000a ? and L\\u000a ? lines in x-ray emission spectra of 3d transition metal oxides was measured. The magnitude of the ratio was found to depend nonmonotonically on the atomic number\\u000a of the 3d elements, with a sharp rise in the middle of the series. In terms of the theory of one-electron resonant x-ray
A CCD-OMA device for the measurement of complete chlorophyll fluorescence emission spectra of leaves during the fluorescence induction kinetics
K. Szab�; H. K. Lichtenthaler; L. Kocs�nyi; P. Richter
Summary A new device for the measurement of complete laser induced fluorescence emission spectra (maxima near 690 and 735 nm) of leaves during the induction of the chlorophyll fluorescence is described. In this the excitation light (cw He\\/Ne laser, 632.8 nm) is switched on by a fast electro-mechanical shutter which provides an opening time of 1 ms. The emitted fluorescence
Determination of the stratospheric organic chlorine budget in the spring arctic vortex from MIPAS B limb emission spectra and air sampling experiments
T. von Clarmann; A. Linden; H. Oelhaf; H. Fischer; F. Friedl-Vallon; C. Piesch; M. Seefeldner; W. V�lker; R. Bauer; A. Engel; U. Schmidt
Vertical profiles of halogenated source gases, CF2Cl2, CFCl3, CHF2Cl, Cl4, and CF4, were retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding, Balloonborne version (MIPAS B) during a balloon flight launched from Esrange near Kiruna, northern Sweden (68�N) on March 14, 1992. This flight was a contribution to the balloon launch program of the European
Stratospheric ClONO2 and HNO3 profiles inside the Arctic vortex from MIPAS-B limb emission spectra obtained during EASOE
H. Oelhaf; T. v. Clarmann; H. Fischer; F. Friedl-Vallon; Ch. Fritzsche; A. Linden; Ch. Piesch; M. Seefeldner; W. V�lker
Vertical profiles of ClONO2 and HNO3 inside the Arctic vortex have been retrieved from infrared limb emission spectra recorded during balloon flights on January 13 and in the night of March 14\\/15, 1992 from Esrange, Sweden (68�N) as part of the European Arctic Stratospheric Ozone Experiment (EASOE). The instrumentation used was the cryogenic Michelson Interferometer for Passive Atmospheric Sounding, Balloon-borne
Emission lines of FeXI in the 257-407� wavelength region observed in solar spectra from EIS\\/Hinode and SERTS
F. P. Keenan; R. O. Milligan; D. B. Jess; K. M. Aggarwal; M. Mathioudakis; R. J. Thomas; J. W. Brosius; J. M. Davila
Theoretical emission-line ratios involving FeXI transitions in the 257-407� wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross-sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291�) and first-order observations (~235-449�) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The
A frequent kinase domain mutation that changes the interaction between PI3K[alpha] and the membrane
Mandelker, Diana; Gabelli, Sandra B.; Schmidt-Kittler, Oleg; Zhu, Jiuxiang; Cheong, Ian; Huang, Chuan-Hsiang; Kinzler, Kenneth W.; Vogelstein, Bert; Amzel, L. Mario; (JHU-MED); (HHMI)
Mutations in oncogenes often promote tumorigenesis by changing the conformation of the encoded proteins, thereby altering enzymatic activity. The PIK3CA oncogene, which encodes p110{alpha}, the catalytic subunit of phosphatidylinositol 3-kinase alpha (PI3K{alpha}), is one of the two most frequently mutated oncogenes in human cancers. We report the structure of the most common mutant of p110{alpha} in complex with two interacting domains of its regulatory partner (p85{alpha}), both free and bound to an inhibitor (wortmannin). The N-terminal SH2 (nSH2) domain of p85{alpha} is shown to form a scaffold for the entire enzyme complex, strategically positioned to communicate extrinsic signals from phosphopeptides to three distinct regions of p110{alpha}. Moreover, we found that Arg-1047 points toward the cell membrane, perpendicular to the orientation of His-1047 in the WT enzyme. Surprisingly, two loops of the kinase domain that contact the cell membrane shift conformation in the oncogenic mutant. Biochemical assays revealed that the enzymatic activity of the p110{alpha} His1047Arg mutant is differentially regulated by lipid membrane composition. These structural and biochemical data suggest a previously undescribed mechanism for mutational activation of a kinase that involves perturbation of its interaction with the cellular membrane.
High-Resolution X-Ray Spectra of the Symbiotic Star SS73 17
NASA Technical Reports Server (NTRS)
Eze, R. N. C.; Luna, G. J. M.; Smith, R. K.
SS73 17 was an innocuous Mira-type symbiotic star until the International Gamma-Ray Astrophysics Laboratory and Swift discovered its bright hard X-ray emission, adding it to the small class of "hard X-ray emitting symbiotics." Suzaku observations in 2006 then showed it emits three bright iron lines as well, with little to no emission in the 0.3-2.0 keV bandpass. We present here follow-up observations with the Chandra High Energy Transmission Grating and Suzaku that confirm the earlier detection of strong emission lines of Fe K(alpha) fluorescence, Fe XXV and Fe XXVI but also show significantly more soft X-ray emission. The high-resolution spectrum also shows emission lines of other highly ionized ions as Si xiv and possibly S XVI. In addition, a re-analysis of the 2006 Suzaku data using the latest calibration shows that the hard (15-50 keV) X-ray emission is brighter than previously thought and remains constant in both the 2006 and 2008 data. The G ratio calculated from the Fe xxv lines shows that these lines are thermal, not photoionized, in origin.With the exception of the hard X-ray emission, the spectra from both epochs can be fit using thermal radiation assuming a differential emission measure based on a cooling-flow model combined with a full and partial absorber. We show that acceptable fits can be obtained for all the data in the 1-10 keV band varying only the partial absorber. Based on the temperature and accretion rate, the thermal emission appears to be arising from the boundary layer between the accreting white dwarf and the accretion disk.
Simulations of the emission spectra of fac-tris(2-phenylpyridine) iridium and Duschinsky rotation effects using the Herman-Kluk semiclassical initial value representation method
NASA Astrophysics Data System (ADS)
Wu, Yinghua; Br�das, Jean-Luc
The phosphorescent emission spectra of fac-tris(2-phenylpyridine) iridium [fac-Ir(ppy)3] due to the lowest triplet T1 and T2 states are simulated using the harmonic oscillator approximation for the S0, T1, and T2 potential energy surfaces (PESs) and taking the Duschinsky rotation into account. The simulations involve the propagation of 177-dimensional wave packets on the coupled PES according to the Herman-Kluk (HK) semiclassical (SC) initial value representation (IVR) method. The HK SC-IVR method is employed because of its accuracy for the PES with mode mixing and its efficiency in dealing with coupled degrees of freedom for large systems. The simulated emission spectrum due to T1 reproduces the structures of the emission spectra observed experimentally, while T2 is found very unlikely to participate in the phosphorescent emission. Although the effect of the Duschinsky mode mixing is small for the T1 state, neglecting it blueshifts the spectrum due to the T2 state by 800 cm-1 and changes the relative intensities, indicating that the importance of the Duschinsky rotation is rather unpredictable and should not be overlooked. The present simulations demonstrate that the simple harmonic oscillator approximation combined with the Duschinsky rotation can adequately describe the photophysics of fac-Ir(ppy)3 and that the HK SC-IVR method is a powerful tool in studies of this kind.
Predicted Fe II Spectra plus UV through sub-mm Emission Line Fluxes for Other Species Arising in Narrow Line Regions of AGNs
NASA Astrophysics Data System (ADS)
Verner, Ekaterina; Bruhweiler, F. C.; Wills, B. J.
Optical and UV spectra indicate pronounced Fe II emission from multitudinous lines superposed on the underlying UV and optical continua of Seyferts and QSOs. Although the intrinsic UV of the these objects exhibit strong Fe II emission arising in higher density Broad Line Region (BLR) gas, observations at visual wavelengths indicate Fe II originating in both BLR and lower density Narrow Line Region (NLR) gas. Our modeling of observed intrinsic UV Fe II emission produces better fits with both BLR and NLR components. We have calculated a grid of photoionization models appropriate for NLR, spanning a range of number density [log (n/cm-3) = 1.0 to 8.0], photoionizing flux [log (?/cm-2 s-1) = 10.0-18.0], microturbulence (? = 0, 2, 10, and 20 km s-1), and abundance (0.1, 0.5, 1.0 and 5 times solar). These models include the effects of cooling from Fe II. The effects of Fe II cooling and the use of a 371 versus an 830-level atom for Fe II in producing the Fe II emission spectra are explored. We present predicted Fe II spectra from the UV through the IR, plus fluxes of important lines of other species from the UV through the sub-mm wavelength range. These predictions, besides being relevant for studies of Fe II in AGNs, provide predicted fluxes for important lines for upcoming missions such as Herschel and SOPHIA. These results will be made available to researchers via the World Wide Web. We acknowledge the support of the National Science Foundation through grant AST-0607465 to CUA.
A time-dependent density-functional theory and complete active space self-consistent field method study of vibronic absorption and emission spectra of coumarin
NASA Astrophysics Data System (ADS)
Li, Junfeng; Rinkevicius, Zilvinas; Cao, Zexing
Time-dependent density-functional theory (TD-DFT) and complete active space multiconfiguration self-consistent field (CASSCF) calculations have been used to determine equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of coumarin. Vertical and adiabatic transition energies of S1, S2, and S3 have been estimated by TD-B3LYP and CASSCF/PT2. Calculations predict that the dipole-allowed S1 and S3 states have a character of 1(??*), while the dipole-forbidden 1(n?*) state is responsible for S2. The vibronic absorption and emission spectra of coumarin have been simulated by TD-B3LYP and CASSCF calculations within the Franck-Condon approximation, respectively. The simulated vibronic spectra show good agreement with the experimental observations available, which allow us to reasonably interpret vibronic features in the S0?S1 and S0?S3 absorption and the S0?S1 emission spectra. Based on the calculated results, activity, intensity, and density of the vibronic transitions and their contribution to the experimental spectrum profile have been discussed.
A time-dependent density-functional theory and complete active space self-consistent field method study of vibronic absorption and emission spectra of coumarin.
Li, Junfeng; Rinkevicius, Zilvinas; Cao, Zexing
Time-dependent density-functional theory (TD-DFT) and complete active space multiconfiguration self-consistent field (CASSCF) calculations have been used to determine equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of coumarin. Vertical and adiabatic transition energies of S1, S2, and S3 have been estimated by TD-B3LYP and CASSCF/PT2. Calculations predict that the dipole-allowed S1 and S3 states have a character of (1)(??*), while the dipole-forbidden (1)(n?*) state is responsible for S2. The vibronic absorption and emission spectra of coumarin have been simulated by TD-B3LYP and CASSCF calculations within the Franck-Condon approximation, respectively. The simulated vibronic spectra show good agreement with the experimental observations available, which allow us to reasonably interpret vibronic features in the S0?S1 and S0?S3 absorption and the S0?S1 emission spectra. Based on the calculated results, activity, intensity, and density of the vibronic transitions and their contribution to the experimental spectrum profile have been discussed. PMID:25005288
DISCOVERY OF Fe K{alpha} X-RAY REVERBERATION AROUND THE BLACK HOLES IN MCG-5-23-16 AND NGC 7314
Zoghbi, A.; Reynolds, C. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Cackett, E. M. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock St, Detroit, MI 48201 (United States); Miniutti, G. [Centro de Astrobiologia (CSIC-INTA), Dep. de Astrosica, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain); Kara, E.; Fabian, A. C., E-mail: email@example.com [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe K{alpha} line peaks, lags the bands at lower and higher energies with a time delay of {approx}1 ks. These lags are unlikely to be due to the narrow Fe K{alpha} line. They are fully consistent with reverberation of the relativistically broadened iron K{alpha} line. The measured lags, their time scale, and spectral modeling indicate that most of the radiation is emitted at {approx}5 and 24 gravitational radii for MCG-5-23-16 and NGC 7314, respectively.
Mutation spectra of smoky coal combustion emissions in Salmonella reflect the TP53 and KRAS mutations in lung tumors from smoky coal-exposed individuals.
Granville, Courtney A; Hanley, Nancy M; Mumford, Judy L; DeMarini, David M
Nonsmoking women in Xuan Wei County, Yunnan Province, China who use smoky coal for cooking and heating in poorly ventilated homes have the highest lung cancer mortality rate in China, and their lung cancer is linked epidemiologically to their use of smoky coal. The emissions contain 81% organic matter, of which 43% is polycyclic aromatic hydrocarbons (PAHs). Exposure assessment and molecular analysis of the lung tumors from nonsmoking women who use smoky coal strongly indicate that PAHs in the emissions are a primary cause of the elevated lung cancer in this population. Here we have determined the mutation spectra of an extract of smoky coal emissions in Salmonella TA98 and TA100; the extract was not mutagenic in TA104. The extract was 8.7 x more mutagenic in TA100 with S9 than without (8.7 rev/microg versus 1.0 rev/microg) and was >3 x more mutagenic in TA100 than in TA98--consistent with a prominent role for PAHs in the mutagenicity of the extract because PAHs are generally more mutagenic in the base-substitution strain TA100 than in the frameshift strain TA98. The extract induced only a hotspot mutation in TA98; another combustion emission, cigarette smoke condensate (CSC), also induces this single class of mutation. In TA100, the mutation spectra of the extract were not significantly different in the presence or absence of S9 and were primarily (78-86%) GC --> TA transversions. This mutation is induced to a similar extent by CSC (78%) and the PAH benzo[a]pyrene (B[a]P) (77%). The frequency of GC --> TA transversions induced in Salmonella by the extract (78-86%) is similar to the frequency of this mutation in the TP53 (76%) and KRAS (86%) genes of lung tumors from nonsmoking women exposed to smoky coal emissions. The mutation spectra of the extract reflect the presence of PAHs in the mixture and support a role for PAHs in the induction of the mutations and tumors due to exposure to smoky coal emissions. PMID:12650907
Redshifts of high-temperature emission lines in the far-ultraviolet spectra of late-type stars. II - New, precise measurements of dwarfs and giants
NASA Technical Reports Server (NTRS)
Ayres, Thomas R.; Jensen, Eberhard; Engvold, Oddbjorn
Results are presented from an IUE SWP camera investigation of the occurrence of gasdynamic flows, analogous to the downdrafts of 10 to the 5th K material observed over magnetic active regions of the sun, among stars of late spectral type. The SWP calibration spectra study conducted documents the existence of local, small, persistent distortions of the echelle wavelength scales that are of unknown origin. Attention is given to the enormous widths of the stellar high-excitation emission lines in both the dwarfs and the giants, with respect to the comparatively small, subsonic Doppler shifts; the widths are typically an order of magnitude greater than the redshifts.
The Equilibrium and Pre-equilibrium Triton Emission Spectra of Some Target Nuclei for ( n, xt) Reactions up to 45 MeV Energy
NASA Astrophysics Data System (ADS)
Tel, E.; Kaplan, A.; Ayd?n, A.; �zkorucuklu, S.; B�y�kuslu, H.; Y?ld?r?m, G.
Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, working out the systematics of ( n,t) reaction cross sections and triton emission differential data are important for the given reaction taking place on various nuclei at different energies. In this study, ( n,xt) reactions for some target nuclei as 16O, 27Al, 59Co and 209Bi have been investigated up to 45 MeV incident neutron energy. In the calculations of the triton emission spectra, the pre-equilibrium and equilibrium effects have been used. The calculated results have been compared with the experimental data taken from the literature.
The effects of side-chain-induced disorder on the emission spectra and quantum yields of oligothiophene nano-aggregates: A combined experimental and MD-TDDFT study
Hong, Jiyun; Sfeir, Matthew Y.; Jeon, SuKyung; Kim, Janice J.; Devi, Diane; Chacon-Madrid, Kelly; Lee, Wynee; Koo, Seung Moh; Wildeman, Jurjen; Peteanu, Linda A.; et al
Oligomeric thiophenes are commonly-used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nano-aggregates of three sexi-thiophene (6T) oligomers having different alkyl substitution patterns were formed using solvent poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changesmore��and their dependence on substitution are well modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain packing configurations within the aggregates, with their measured electronic spectra.��less
The effects of side-chain-induced disorder on the emission spectra and quantum yields of oligothiophene nano-aggregates: A combined experimental and MD-TDDFT study
Hong, Jiyun [Carnegie Mellon Univ., Pittsburgh, PA (United States); Sfeir, Matthew Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Jeon, SuKyung [Carnegie Mellon Univ., Pittsburgh, PA (United States); Kim, Janice J. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Devi, Diane [Carnegie Mellon Univ., Pittsburgh, PA (United States); Chacon-Madrid, Kelly [Carnegie Mellon Univ., Pittsburgh, PA (United States); Lee, Wynee [Carnegie Mellon Univ., Pittsburgh, PA (United States); Koo, Seung Moh [Carnegie Mellon Univ., Pittsburgh, PA (United States); Wildeman, Jurjen [Zernike Institute of Advanced Materials Nijenborgh, Groningen (The Netherlands); Peteanu, Linda A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Wen, Jin [Najing Univ., Nanjing (China); Ma, Jing [Najing Univ., Nanjing (China)
Oligomeric thiophenes are commonly-used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nano-aggregates of three sexi-thiophene (6T) oligomers having different alkyl substitution patterns were formed using solvent poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changes and their dependence on substitution are well modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain packing configurations within the aggregates, with their measured electronic spectra.
Fluorescent excitation of Fe 2, Mn 2, Ti 2, N 1 lines by V 4, N 5, O 6: Emission lines in the spectra of symbiotic stars and Seyfert galaxies
NASA Technical Reports Server (NTRS)
Gilra, D. P.
Analysis of the published IUE and ground based high resolution spectra of symbiotic stars, particularly RR Tel, shows that the dominant excitation mechanism of Fe II, Mn II, Ti II, and N I lines is the selective fluorescent excitation of some levels by the strong C IV, N V, and O VI emission lines. The same mechanism should work for the excitation of Fe II lines in the spectra of Seyfert galaxies and Q60's whose emission spectra are quite similar to those of symbiotic stars. The similarities and differences between the fluroescent excitation mechanism reported herein and the Bowen's mechanism is analyzed.
A new mechanism of origination of additional components in hydrogen emission lines in the spectra of AGN
V. A. Ambartsumian; E. Ye. Khachikian; N. B. Yengibarian
The appearance of additional new emission components of Hydrogen lines in the spectrum of AGN first was discovered in 1969 by Khachikian & Weedman (Ap.J., Letters, 164, L109, 1971). During one year (between February of 1968 and January 1969) in the spectrum of Sy2 galaxy Mark.6 the new broad emission components of Halpha, Hbeta, Hgamma, blue-shifted on 3000 km\\/s have
Lines and continuum sky emission in the near infrared: observational constraints from deep high spectral resolution spectra with GIANO-TNG
Oliva, E; Scuderi, S; Benatti, S; Carleo, I; Lapenna, E; Mucciarelli, A; Baffa, C; Biliotti, V; Carbonaro, L; Falcini, G; Giani, E; Iuzzolino, M; Massi, F; Sanna, N; Sozzi, M; Tozzi, A; Ghedina, A; Ghinassi, F; Lodi, M; Harutyunyan, A; Pedani, M
Aims Determining the intensity of lines and continuum airglow emission in the H-band is important for the design of faint-object infrared spectrographs. Existing spectra at low/medium resolution cannot disentangle the true sky-continuum from instrumental effects (e.g. diffuse light in the wings of strong lines). We aim to obtain, for the first time, a high resolution infrared spectrum deep enough to set significant constraints on the continuum emission between the lines in the H-band. Methods During the second commissioning run of the GIANO high-resolution infrared spectrograph at La Palma Observatory, we pointed the instrument directly to the sky and obtained a deep spectrum that extends from 0.97 to 2.4 micron. Results The spectrum shows about 1500 emission lines, a factor of two more than in previous works. Of these, 80% are identified as OH transitions; half of these are from highly excited molecules (hot-OH component) that are not included in the OH airglow emission models normally used for astronomical ...
HIGH-RESOLUTION ELECTRON-IMPACT EMISSION SPECTRA AND VIBRATIONAL EMISSION CROSS SECTIONS FROM 330-1100 nm FOR N{sub 2}
Mangina, Rao S.; Ajello, Joseph M.; West, Robert A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dziczek, Dariusz [Institute of Physics, Nicolaus Copernicus University, Torun (Poland)
Electron-impact emission cross sections for N{sub 2} were measured in the wavelength range of 330-1100 nm at 25 eV and 100 eV impact energies. Cross sections of several molecular emission bands of the first positive band system B {sup 3}{Pi}{sub g} {sup +}({nu}') {yields} A {sup 3}{Sigma}{sub g} {sup +}({nu}'') and the second positive band system C {sup 3}{Pi}{sub u} ({nu}') {yields} B {sup 3}{Pi}{sub g} ({nu}'') of N{sub 2}, the first negative band (1NB) system B {sup 2}{Sigma}{sub u} {sup +}({nu}') {yields} X {sup 2}{Sigma}{sub g} {sup +}({nu}'') and Meinel band system A {sup 2}{Pi}{sub u} ({nu}') {yields} X {sup 2}{Sigma}{sub g} {sup +}({nu}'') of N{sub 2} {sup +} ions as well as line emissions of N (N I) and N{sup +} (N II) in the visible-optical-near-IR wavelength range reported in this work were measured for the first time in a single experimental setup at high spectral resolving power ({lambda}/{Delta}{lambda} {approx} 10000) under single-collision-scattering geometry and optically thin conditions. Rotational emission lines of N{sub 2} and N{sub 2} {sup +} were observed for strong emission bands at a gas temperature of about 300 K. The absolute cross section of the strongest (0,0) vibrational band at 391.43 nm of 1NB was determined using the standard H{sub {alpha}} emission cross sections of H{sub 2} by electron impact at both 25 eV and 100 eV electron-impact energies, and the cross sections for the remainder of the emissions were determined using (0,0) 1NB value. A comparison of the present emission cross sections with the earlier published data from both electron energy loss and electron-impact-induced fluorescence emission is discussed.
Prediction of the hydrophilic antioxidant capacity of tomato pastes from the IR and fluorescence excitation-emission spectra of extracts and intact samples.
Orzel, Joanna; Stanimirova, Ivana; Czarnik-Matusewicz, Boguslawa; Daszykowski, Michal
The performance of the recently proposed excitation-emission fluorescence method was compared to the method using infrared measurements for the evaluation of the antioxidant properties of intact samples and extracts that had been obtained from tomato pastes. The oxygen radical absorbance capacity assay (ORAC) was applied in order to estimate the antioxidant capacity of the extracts, while the Folin-Ciocalteu reagent was adopted for the evaluation of the total phenolic content. The optimal extraction conditions for tomato pastes (three minutes of sonication under 80�C) were determined using the central composite design. Chemometric models such as the partial least squares regression and its N-way variant were further constructed in order to predict the antioxidant capacity or total phenolic content of the samples using either the IR or fluorescence spectra. The prediction errors that were obtained for the total antioxidant content were evaluated as the Trolox equivalents from the ORAC assay and were found to be equal to 2.011 (14.21%) for the fluorescence and 2.426 (17.15%) for the IR spectra, respectively. The prediction errors of the total phenolic content expressed as gallic acid equivalents were 0.067 (10.78%) for the fluorescence and 0.033 (5.36%) for the IR spectra, which were used as independent variables in the regression models. PMID:25863373
Local H~{\\sc i} emissivity measured with the {\\it Fermi}-LAT and implications for cosmic-ray spectra
Casandjian, Jean-Marc
Cosmic-ray (CR) electrons and nuclei interact with the Galactic interstellar gas and produce high-energy $\\gamma$ rays. The $\\gamma$-ray emission rate per hydrogen atom, called emissivity, provides a unique indirect probe of the CR flux. We present the measurement and the interpretation of the emissivity in the solar neighborhood for $\\gamma$-ray energy from 50~MeV to 50~GeV. We analyzed a subset of 4 years of observations from the Large Area Telescope (LAT) aboard the {\\it Fermi Gamma-ray Space Telescope} ({\\it Fermi}) restricted to absolute latitudes $10^o<|b| <70^o$. From a fit to the LAT data including atomic, molecular and ionized hydrogen column density templates as well as a dust optical depth map we derived the emissivities, the molecular hydrogen to CO conversion factor $X_{CO}=(0.902\\pm0.007) \\times 10^{20}$ cm$^{-2}$ (K km s$^{-1}$)$^{-1}$ and the dust-to-gas ratio $X_{DUST}=(41.4\\pm0.3) \\times 10^{20}$ cm$^{-2}$ mag$^{-1}$. Moreover we detected for the first time $\\gamma$-ray emission from i...
Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma
NASA Astrophysics Data System (ADS)
Hansen, S. B.; Colgan, J.; Faenov, A. Ya.; Abdallah, J.; Pikuz, S. A.; Skobelev, I. Yu.; Wagenaars, E.; Booth, N.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Evans, R. G.; Gray, R. J.; Kaempfer, T.; Lancaster, K. L.; McKenna, P.; Rossall, A. K.; Schulze, K. S.; Uschmann, I.; Zhidkov, A. G.; Woolsey, N. C.
X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.
Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma
Hansen, S. B., E-mail: firstname.lastname@example.com, E-mail: email@example.com [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Colgan, J.; Abdallah, J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Faenov, A. Ya., E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto 619-0215 (Japan); Pikuz, S. A.; Skobelev, I. Yu. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation)] [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Wagenaars, E.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Rossall, A. K.; Woolsey, N. C. [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)] [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom); Booth, N.; Lancaster, K. L. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom)] [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Evans, R. G. [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom)] [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); Gray, R. J.; McKenna, P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 ONG (United Kingdom)] [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 ONG (United Kingdom); Kaempfer, T.; Schulze, K. S. [Helmholtzinstitut Jena, Jena D-07743 (Germany)] [Helmholtzinstitut Jena, Jena D-07743 (Germany); Uschmann, I. [Helmholtzinstitut Jena, Jena D-07743 (Germany) [Helmholtzinstitut Jena, Jena D-07743 (Germany); Institut f�r Optik und Quantenelektronic, Friedrich-Schiller-Universit�t Jena, Max-Wien Platz 1, Jena, D-07743 (Germany); and others
X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.
The ground-based H, K, and L-band absolute emission spectra of HD 209458b
Zellem, Robert T; Deroo, Pieter; Swain, Mark R; Waldmann, Ingo P
Here we explore the capabilities of NASA's 3.0 meter Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 meter Hale telescope with the TripleSpec spectrometer with near-infrared H, K, and L-band measurements of HD 209458b's secondary eclipse. Our IRTF/SpeX data are the first absolute L-band spectroscopic emission measurements of any exoplanet other than the hot Jupiter HD 189733b. Previous measurements of HD 189733b's L-band indicate bright emission hypothesized to result from non-LTE CH$_{4}$ $\
Compressed shell conditions extracted from spectroscopic analysis of Ti K-shell absorption spectra with evaluation of line self-emission
NASA Astrophysics Data System (ADS)
Johns, H. M.; Mancini, R. C.; Hakel, P.; Nagayama, T.; Smalyuk, V. A.; Regan, S. P.; Delettrez, J.
Ti-doped tracer layers embedded in the shell at varying distances from the fuel-shell interface serve as a spectroscopic diagnostic for direct-drive experiments conducted at OMEGA. Detailed modeling of Ti K-shell absorption spectra produced in the tracer layer considers n = 1-2 transitions in F- through Li-like Ti ions in the 4400-4800 eV range, both including and excluding line self-emission. Testing the model on synthetic spectra generated from 1-D LILAC hydrodynamic simulations reveals that the model including self-emission best reproduces the simulation, while the model excluding self-emission overestimates electron temperature Te and density Ne to a higher degree for layers closer to the core. The prediction of the simulation that the magnitude of Te and duration of Ti absorption will be strongly tied to the distance of the layer from the core is consistent with the idea that regions of the shell close to the core are more significantly heated by thermal transport out of the hot dense core, but more distant regions are less affected by it. The simulation predicts more time variation in the observed Te, Ne conditions in the compressed shell than is observed in the experiment, analysis of which reveals conditions remain in the range Te = 400-600 eV and Ne = 3.0-10.0 � 1024 cm-3 for all but the most distant Ti-doped layer, with error bars �5% Te value and �10% Ne on average. The Te, Ne conditions of the simulation lead to a greater degree of ionization for zones close to the core than occurs experimentally, and less ionization for zones far from the core.
Log-parabolic spectra and particle acceleration in blazars. III: SSC emission in the TeV band from Mkn 501
E. Massaro; A. Tramacere; M. Perri; P. Giommi; G. Tosti
Curved broad-band spectral distributions of non-thermal sources like blazars are described well by a log-parabolic (LP) law where the second degree term measures the curvature. LP energy spectra can be obtained for relativistic electrons by means of a statistical acceleration mechanism whose probability of acceleration depends on energy. In this paper we compute the spectra radiated by an electron population via synchrotron (S) and Synchro-Self Compton(SSC) processes to derive the relations between the LP parameters. These spectra were obtained by means of an accurate numerical code. We found that the ratio between the curvature parameters of the S spectrum to that of the electrons is equal to about 0.2 instead of 0.25, the value foreseen in the delta approximation. Inverse Compton spectra are also intrinsically curved and can be approximated by a log-parabola only in limited ranges. The curvature parameter, estimated around the SED peak, may vary from a lower value than that of the S spectrum up to that of emitting electrons depending on whether the scattering is in the Thomson or in the Klein-Nishina regime. We applied this analysis to computing the SSC emission from the BL Lac object Mkn 501 during the large flare of April 1997. We fit simultaneous BeppoSAX and CAT data and reproduced intensities and spectral curvatures of both components with good accuracy. The large curvature observed in the TeV range was found to be mainly intrinsic, and therefore did not require a large pair production absorption against the extragalactic background. We regard this finding as an indication that the Universe is more transparent at these energies than previously assumed by several models found in the literature. This conclusion is supported by recent detection of two relatively high redshift blazars with H.E.S.S.
Cospatial Longslit UV-Optical Spectra of Ten Galactic Planetary Nebulae with HST STIS: Description of observations, global emission-line measurements, and empirical CNO abundances
NASA Astrophysics Data System (ADS)
Dufour, R. J.; Kwitter, K. B.; Shaw, R. A.; Balick, B.; Henry, R. B. C.; Miller, T. R.; Corradi, R. L. M.
This poster describes details of HST Cycle 19 (program GO 12600), which was awarded 32 orbits of observing time with STIS to obtain the first cospatial UV-optical spectra of 10 Galactic planetary nebulae (PNe). The observational goal was to measure the UV emission lines of carbon and nitrogen with unprecedented S/N and wavelength and spatial resolution along the disk of each object over a wavelength range 1150-10270 Ang . The PNe were chosen such that each possessed a near-solar metallicity but the group together spanned a broad range in N/O. This poster concentrates on describing the observations, emission-line measurements integrated along the entire slit lengths, ionic abundances, and estimated total elemental abundances using empirical ionization correction factors and the ELSA code. Related posters by co-authors in this session concentrate on analyzing CNO abundances, progenitor masses and nebular properties of the best-observed targets using photoionization modeling of the global emission-line measurements [Henry et al.] or detailed analyses of spatial variations in electron temperatures, densities, and abundances along the sub arcsecond resolution slits [Miller et al. & Shaw et al.]. We gratefully acknowledge AURA/STScI for the GO 12600 program support, both observational and financial.
An iterative method in a probabilistic approach to the spectral inverse problem. Differential emission measure from line spectra and broadband data
NASA Astrophysics Data System (ADS)
Goryaev, F. F.; Parenti, S.; Urnov, A. M.; Oparin, S. N.; Hochedez, J.-F.; Reale, F.
Context. Inverse problems are of great importance in astrophysics, e.g., for deriving information about the physical characteristics of hot optically thin plasma sources from their extreme ultraviolet and X-ray spectra. Aims: We describe and test an iterative method developed within the framework of a probabilistic approach to the spectral inverse problem for determining the thermal structures of the emitting plasma. We also demonstrate applications of this method to both high resolution line spectra and broadband imaging data. Methods: Our so-called Bayesian iterative method (BIM) is an iterative procedure based on Bayes' theorem and is used to reconstruct differential emission measure (DEM) distributions. Results: To demonstrate the abilities of the BIM, we performed various numerical tests and model simulations establishing its robustness and usefulness. We then applied the BIM to observable data for several active regions (AR) previously analyzed with other DEM diagnostic techniques: both SUMER/SOHO (Landi & Feldman 2008, ApJ, 672, 674) and SPIRIT/CORONAS-F (Shestov et al. 2010, Astron. Lett., 36, 44) line spectra data, and XRT/Hinode (Reale et al. 2009, ApJ, 698, 756) broadband imaging data. The BIM calculations confirmed the main results for SUMER/SOHO data showing very good quantitative agreement between both DEMs at log T ? 6.5 (T is the temperature in units of Kelvin) and a slight shift for two maxima at lower temperatures with ?30-50% difference in the DEM values for the coolest peak. For the SPIRIT data, we revised and validated AR DEM results including the inference of hot plasma in ARs with an emission measure (EM) at temperatures ?9-15 MK comparable to the EM at ?2-4 MK. In the case of XRT broadband data, the BIM solutions provided evidence of hot plasma at temperatures ?4-6 MK with EM up to ~30% as compared to that at ?2-4 MK in a non-flaring AR on 2006 November 12. Conclusions: The BIM results show that this method is an effective tool for determining the thermal structure of emitting plasma and can be successfully used for the DEM analysis of both line spectra and broadband imaging data. The BIM calculations correlate with recent studies confirming the existence of hot plasma in solar ARs. The BIM results also indicate that the coronal plasma may have the continuous distributions predicted by the nanoflare paradigm.
The use of the bulk properties of gamma-ray burst prompt emission spectra for the study of cosmology
NASA Astrophysics Data System (ADS)
Goldstein, Adam
The study of bulk spectral properties of Gamma-Ray Bursts (GRBs) is important to understanding the physics behind these powerful explosions and may even be an aide in studying cosmology. The prompt emission spectral properties have long been studied by a growing community of researchers, and many theories have been developed since the discovery of GRBs. Even though the exact physics of these phenomena is not completely understood, GRBs have been proposed to give insight on other astrophysical phenomena from dark matter to the expansion of the universe. Obviously, using GRBs to study cosmology requires a large sample size to adequately constrain results and provide confident conjectures. For this reason, BATSE and GBM results are paramount to the study of the prompt emission of GRBs. Using results from both instruments, I study the bulk spectral properties of GRBs and describe analysis techniques that can be used to study cosmology.
Ab initio calculation of X-ray emission and IR spectra of the hydrofullerene C 60H 36
NASA Astrophysics Data System (ADS)
Bulusheva, L. G.; Okotrub, A. V.; Antich, A. V.; Lobach, A. S.
Two isomers of the hydrofullerene C 60H 36 with T and D3 d symmetry were calculated using ab initio Hartree-Fock self-consistent field (HF-SCF). The T symmetry isomer in which the benzenoid rings occupy tetrahedral positions is predicted to be lower in energy than the other considered isomer. Simulated CK ? spectra of the isomers were compared with the X-ray fluorescence spectrum of the hydrofullerene C 60H 36 prepared by the transfer hydrogenation method. The short-wave maximum intensity of the CK ? spectrum of C 60H 36 was shown to be sensitive to the number of ? electrons in the high-occupied levels of the molecule. Although the theoretical spectra are similar in appearance, the T isomer seems to be in better accordance with the experiment. Furthermore, the computed infrared frequencies and intensities for this isomer were found to correlate well with features in the measured spectrum of C 60H 36. The most intense peak in the low-frequency spectral region was shown to correspond to the skeletal vibrations of the benzenoid rings.
Influence of thermal treatments on glow curve and thermoluminescence emission spectra of LiF:Mg,Cu,P
K. Meijvogel; A. J. J. Bos
LiF:Mg,Cu,P is a highly sensitive thermoluminescence material, but loses its sensitivity if annealed at temperatures above 513 K. In this paper, the effects of these annealing temperatures on GR-200A samples are investigated and quantified. The changes in the glow curve and the emission spectrum are investigated as a function of annealing temperature and cooling rate. The return of up to
Application of PARAFAC for calibration with excitation-emission matrix fluorescence spectra of three classes of environmental pollutants
Greger G. Andersson; Karl S. Booksh
SUMMARY Parallel factor analysis (PARAFAC) is applied to three calibrations of a field-portable, cuvette-based, single- measurement, excitation-emission matrix fluorometer. In the first example the fluorometer is calibrated based on interactions between a non-fluorescent DDT-type pesticide and a fluorescent dye. PARAFAC is employed to deconvolve the fluorescence profiles of dissociated and complexed dye states. Calibration is performed based on the intensity
Detection of Copper (II) and Cadmium (II) binding to dissolved organic matter from macrophyte decomposition by fluorescence excitation-emission matrix spectra combined with parallel factor analysis.
Yuan, Dong-Hai; Guo, Xu-Jing; Wen, Li; He, Lian-Sheng; Wang, Jing-Gang; Li, Jun-Qi
Fluorescence excitation-emission matrix (EEM) spectra coupled with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM) derived from macrophyte decomposition, and to study its complexation with Cu (II) and Cd (II). Both the protein-like and the humic-like components showed a marked quenching effect by Cu (II). Negligible quenching effects were found for Cd (II) by components 1, 5 and 6. The stability constants and the fraction of the binding fluorophores for humic-like components and Cu (II) can be influenced by macrophyte decomposition of various weight gradients in aquatic plants. Macrophyte decomposition within the scope of the appropriate aquatic phytomass can maximize the stability constant of DOM-metal complexes. A large amount of organic matter was introduced into the aquatic environment by macrophyte decomposition, suggesting that the potential risk of DOM as a carrier of heavy metal contamination in macrophytic lakes should not be ignored. PMID:25969375
Spectral correspondence between visual spectral sensitivity and bioluminescence emission spectra in the click beetle Pyrophorus punctatissimus (Coleoptera: Elateridae).
Lall; Ventura; Bechara; de Souza JM; Colepicolo-Neto; Viviani
The presence of two spectral mechanisms, near-ultraviolet and green (lambda(max)=545nm), is strongly suggested by electroretinographic visual spectral sensitivity curves obtained under dark and red chromatic adaptation conditions in the compound eyes of the click beetle Pyrophorus punctatissimus. The bioluminescence emission of the dorsal prothoracic lanterns is deep green (lambda(max)=543nm) and that of the ventral abdominal lantern is lime green (lambda(max)=556nm) in colour in P. punctatissimus. A broad green visual receptor would detect both deep green and lime green bioluminescent optical signals. PMID:10817840
OH(A 2?+) and rare gas-deuteride (NeD, ArD) excimers generated in microcavity plasmas: Ultraviolet emission spectra and formation kinetics
NASA Astrophysics Data System (ADS)
Ricconi, B. J.; Park, S.-J.; Sung, S. H.; Tchertchian, P. A.; Eden, J. G.
Emission in the ultraviolet from the A?+2 electronic excited states of OH, NeD, and ArD, and the formation kinetics of these excited heteronuclear diatomics, have been investigated in microcavity plasmas generated in rare gas/H2O or D2 gas mixtures. Excitation transfer from the a?u +3(1u,0u-) Rydberg state of Ar2 appears to be the dominant pathway to OH(A?+2) formation in Ar /H2O vapor mixtures with total pressures of 400-800Torr and H2O partial pressures of 100mTorr-3Torr. Maximum emission on the (v',v?)=(0,0) vibrational band of the OH(A ?X) transition is observed in a 25?m, 45nl microcavity for 600-800Torr Ar/0.5Torr H2O mixtures. Comparisons of experimental and simulated fluorescence spectra show the OH[A?+2(v'=0)] state rotational temperature to be 425K for 600Torr Ar/100mTorr H2O mixtures but to rise linearly with the H2O partial pressure and exhibit a slope of 170K/Torr H2O for 100mTorr?pH2O?3Torr. Excitation of Ne or Ar /D2 gas mixtures in 50�50 arrays of Si microplasma devices generates broadband spectra, peaking in the mid-ultraviolet (?�280-320nm), which are attributed to the A ?X transition of the ArD or NeD excimers. The optimal D2 concentration is observed to be �0.5% and the primary kinetic formation mechanism for the deuterides involves D atom transfer in collisions between Ar(4sP3) and D2.
Simulation of the A-X and B-X transition emission spectra of the InCl molecule in low pressure plasmas
NASA Astrophysics Data System (ADS)
Briefi, S.; Fantz, U.
Low pressure plasmas containing indium halides as radiators are discussed for lighting applications as an efficient alternative to mercury-containing fluorescent lamps. To gain insight into plasma parameters like the vibrational and rotational temperature of the molecule, the near UV emission spectra of the indium halides arising from the A?0+3?X?+1 and the B?13?X?+1 transitions are simulated. Such a simulation requires Franck-Condon factors and vibrationally resolved transition probabilities which are not available in the literature for InCl. Therefore, they have been calculated by solving the Schr�dinger equation using the Born-Oppenheimer approximation. The values of the Franck-Condon factors and the transition probabilities are presented. For the A-X transition a good match of the simulated and measured spectra could be achieved but for the B-X transition neither the relative intensity nor the wavelength could be reproduced. This indicates that for the B state the values of the molecular constants, the potential curve and/or the electronic dipole transition moment of the B-X transition are inaccurate. Despite this mismatch the rotational and vibrational temperatures of the molecule can still be determined using the A-X transition.
Determination of trace-gas amounts in plumes by the use of orthogonal digital filtering of thermal-emission spectra
NASA Astrophysics Data System (ADS)
Hayden, Andreas; Niple, Edward; Boyce, Bruce
The thermal emission of gases in a plume can be measured by a Fourier-transform spectrometer that is located some distance from the plume. In order to measure quantitatively the amount of a particular gas of interest, in general a large spectrally structured background must be removed. Differencing techniques, in which a measured background spectrum is subtracted from a measured spectrum believed to contain a target, often do not remove background spectral features adequately. The inadequacy of two-spectrum differencing techniques is due to the spatial and the temporal variations in a scene. We present a method by which to reduce spatial and temporal spectral clutter to instrument random noise, allowing the measurement of gas amounts in an effluent plume. The method is applied to simulated data and field data to show its effectiveness.
Hamaguchi, Kenji [CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Grosso, Nicolas [Universite de Strasbourg, Observatoire Astronomique de Strasbourg, 11 rue de l'universite, 67000 Strasbourg (France); Kastner, Joel H.; Richmond, Michael [Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Weintraub, David A. [Vanderbilt University, Nashville, TN 37235 (United States)], E-mail: firstname.lastname@example.com
The Suzaku X-ray satellite observed the young stellar object (YSO) V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in 2008 August. During the 87 ks observation with a net exposure of 40 ks, V1647 Ori showed a high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other YSOs. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT {approx} 5 keV). It also shows a fluorescent iron K{alpha} line with a remarkably large equivalent width (EW) of {approx}600 eV. Such a large EW suggests that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron K{alpha} line, so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.
X-ray Emission from the Host Clusters of Powerful AGN
Hall, P B; Green, R F; Hall, Patrick B.; Ellingson, Erica; Green, Richard F.
(Abridged) We report the detection of X-ray emission from the host cluster of the radio-quiet quasar H1821+643 with the ROSAT HRI, and the non-detection of the host cluster of the radio-loud quasar 3C206 using the EINSTEIN HRI. CL1821+643 has a rest-frame 0.1-2.4 keV luminosity of 3.74$\\pm$0.57 h$_{50}^{-2}$ 10^45 ergs/sec, 38% from a barely resolved cooling flow component, which places it among the most X-ray luminous clusters known. The cluster emission complicates interpretation of previous X-ray spectra of this field; in particular, the observed FeK$\\alpha$ emission can probably be attributed entirely to the cluster, and either the quasar is relatively X-ray quiet for its optical luminosity or the cluster has a relatively low temperature for its luminosity. We combine these data with the recent detection of X-ray emission from the host cluster of the `buried' radio-quiet quasar IRAS 09104+4109, our previous upper limits for the host clusters of two z$\\sim$0.7 RLQs, and literature data on FR II radio galax...
Asymptotically-Equal-To 10 eV ionization shift in Ir K{alpha}{sub 2} from a near-coincident Lu K-edge
Pereira, N. R. [Ecopulse, Inc, P.O. Box 528, Springfield, Virginia 22150 (United States); Weber, B. V.; Phipps, D.; Schumer, J. W. [Naval Research Laboratory, Washington, DC 20375 (United States); Seely, J. F. [Artep Inc., 2922 Excelsior Springs Ct, Ellicott City, Maryland 21042 (United States); Carroll, J. J. [Army Research Laboratory, Adelphi, Maryland 20873 (United States); VanHoy, J. R. [United States Naval Academy, Annapolis, Maryland 21402 (United States); Slabkowska, K.; Polasik, M. [Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Torun (Poland)
Close to an x-ray filter's K-edge the transmission depends strongly on the photon energy. For a few atom pairs, the K-edge of one is only a few tens of eV higher than a K-line energy of another, so that a small change in the line's energy becomes a measurable change in intensity behind such a matching filter. Lutetium's K-edge is Asymptotically-Equal-To 27 eV above iridium's K{alpha}{sub 2} line, Asymptotically-Equal-To 63.287 keV for cold Ir. A Lu filter reduces this line's intensity by Asymptotically-Equal-To 10 % when it is emitted by a plasma, indicating an ionization shift {Delta}E Asymptotically-Equal-To 10{+-}1 eV.
Emission spectra from ArF laser ablation of high T/sub c/ superconductor Bi/sub 2/CaSr/sub 2/Cu/sub 2/O/sub 9/
Deshmukh, S.; Rothe, E.W.; Reck, G.P.; Kushida, T.; Xu, Z.G.
A 193 nm excimer laser is used to ablate a Bi/sub 2/CaSr/sub 2/Cu/sub 2/O/sub 9/ superconductor and samples of Bi/sub 2/O/sub 3/, CaO, CuO, and Sr(OH)/sub 2/x8H/sub 2/O. Emission spectra generated during ablation are presented. These emissions are from simple atomic and diatomic species. Our observations show that the emission can be used to characterize the bulk material.
Iron K-shell emission from NGC 1068
Band, D.L.; Klein, R.I.; Castor, J.I.; Nash, J.K. (California Univ., Berkeley (USA) Lawrence Livermore National Laboratory, CA (USA))
The X-ray iron line emission from NGC 1068 is modeled using the new multiline, multilevel, non-LTE radiative transport code Altair and a detailed atomic model for Ne-like through-stripped iron. The X-rays passing through the ionized gas induce iron K-alpha line emission. The atomic model was constructed to describe in detail the K-shell ionization and K-alpha line emission, as well as to calculate the ionization state properly. A greater equivalent width than previously predicted is found because the observed K-alpha line is produced not only by fluorescence but also by line scattering of the continuum into the line of sight. The K-alpha equivalent width and energy are functions not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGC 1068, it is found that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance. 35 refs.
Iron K-shell emission from NGC 1068
NASA Technical Reports Server (NTRS)
Band, David L.; Klein, Richard I.; Castor, John I.; Nash, J. K.
The X-ray iron line emission from NGC 1068 is modeled using the new multiline, multilevel, non-LTE radiative transport code Altair and a detailed atomic model for Ne-like through-stripped iron. The X-rays passing through the ionized gas induce iron K-alpha line emission. The atomic model was constructed to describe in detail the K-shell ionization and K-alpha line emission, as well as to calculate the ionization state properly. A greater equivalent width than previously predicted is found because the observed K-alpha line is produced not only by fluorescence but also by line scattering of the continuum into the line of sight. The K-alpha equivalent width and energy are functions not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGC 1068, it is found that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance.
Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku
NASA Technical Reports Server (NTRS)
Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.; Yamaguchi, Hiroya
X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant s rim are depleted to approx.0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to approx. 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at approx.0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O K(alpha) appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question. Subject headings: ISM: abundances ISM: individual objects (Cygnus Loop) ISM: supernova remnants X-rays: ISM atomic processes
Comparison of calculated spectra for the interaction of photons in a liquid scintillator. Example of 54Mn 835 keV emission.
Cassette, P; Ahn, G H; Alzitzoglou, T; Aubineau-Lani�ce, I; Bochud, F; Garcia Torano, E; Grau Carles, A; Grau Malonda, A; Kossert, K; Lee, K B; Laedermann, J P; Simpson, B R S; van Wyngaardt, W M; Zimmerman, B E
The CIEMAT/NIST and TDCR methods in liquid scintillation counting, initially developed for the activity standardization of pure-beta radionuclides, have been extended to the standardization of electron capture and beta-gamma radionuclides. Both methods require the calculation of the energy spectrum absorbed by the liquid scintillator. For radionuclides emitting X-rays or gamma-rays, when the energy is greater than a few tens of keV the Compton interaction is important and the absorption is not total. In this case, the spectrum absorbed by the scintillator must be calculated using analytical or stochastic models. An illustration of this problem is the standardization of 54Mn, which is a radionuclide decaying by electron capture. The gamma transition, very weakly converted, leads to the emission of an 835 keV photon. The calculation of the detection efficiency of this radionuclide requires the calculation of the energy spectrum transferred to the scintillator after the absorption of the gamma ray and the associated probability of absorption. The validity of the method is thus dependent on the correct calculation of the energy transferred to the scintillator. In order to compare the calculation results obtained using various calculation tools, and to provide the metrology community with some information on the choice of these tools, the LS working group of the ICRM organised a comparison of the calculated absorbed spectra for the 835 keV photon of 54Mn. The result is the spectrum of the energy absorbed by the scintillator per emission of an 835 keV gamma ray. This exercise was proposed for a standard 20 ml LS glass vial and for LS cocktail volumes of 10 and 15 ml. The calculation was done for two different cocktails: toluene and a widely used commercial cocktail, Ultima Gold. The paper describes the results obtained by nine participants using a total of 12 calculation codes. PMID:16600600
Monitoring Disinfection Byproduct Forming Potential with Simultaneous Absorbance Spectra and Fluorescence Excitation-Emission Mapping: Supporting Stage 2 EPA Regulation Monitoring Compliance
NASA Astrophysics Data System (ADS)
Gilmore, A. M.
Water treatment plants in the United States will soon (by 2013 to 2013) be required to initialize enhanced monitoring for reducing disinfection by-products (DBPs) to meet the Stage 2 levels enforced by the EPA. The key to successfully meeting these requirements lies in the treatment plant's ability to deal with often dramatic source-water variations in natural organic matter (NOM) content. Whereas the regulated levels of NOM must be determined by measuring total organic carbon (TOC) often this parameter does not provide rapid or cost-effective qualitative or quantitative assessment of the various humic, fulvic and other aromatic NOM components. However, 2 main optical techniques namely UV absorbance and fluorescence excitation-emission mapping can be used for rapid assessment with precise identification of humic and fulvic components. This study presents data from a new type of instrument which simultaneously measures the UV-VIS absorbance spectrum and EEM. The rapid absorbance-EEM is facilitated by a single system that is more than 100 time faster than conventional scanning absorbance and fluoresence optical benches. The new system can continuously collect EEMs and absorbance spectra at a rate often greater than 1 per min with the extra capacity to monitor the UV254 absorbance and fluorescence emission spectrum excited at 254 nm in 4 ms intervals (an equivalent scan rate of 5.5 million nm/min). The EEM spectral data is corrected for all instrumental response factors including concentration dependent inner-filter effects. The accumulated EEM data sets can be modeled using conventional peak identification, PARAFAC and or PCA analysis of the fractionated samples to predict the trihalomethane forming potential (THMFP). This study compares the effectiveness of THFMP predictive models based on these three techniques and explains how these can be readily employed to facilitate the Stage 2 regulation compliance for DBP monitoring.
Phase dependence of relativistic electron dynamics and emission spectra in the superposition of an ultraintense laser field and a strong uniform magnetic field.
He, Xinkui; Shuai, B; Ge, X C; Li, R X; Xu, Z Z
The phase dependence of the dynamics and emission spectra of a fully relativistic electron in the superposition of an ultraintense plane wave laser field and a strong uniform magnetic field has been investigated. It is found that the effect of changing the initial laser phase is quite different for circularly and linearly polarized laser fields. For circular polarization only the axis of the helical trajectory is changed with variation of the initial laser field phase. However, for linear polarization, the effect of changing the initial phase is opposite in the two parameter regions divided by the resonance condition r=1 (r stands for the ratio between the reduced cyclotron frequency and laser frequency). When r<1, with increase in the initial laser field phase eta(0) from 0 to pi/2, both the radius of the electron's helical trajectory and the height of the peak related to the uniform magnetic field are decreased, and these two physical values are increased with an increase in the laser initial phase when r>1. The phase dependence of the electron's energy and velocity components was also studied. Some beat structure is found when eta(0)=0 and this structure is absent when eta(0)=pi/2. PMID:14682898
Non-LTE modeling of narrow emission components of He and Ca lines in optical spectra of classical T Tauri stars
NASA Astrophysics Data System (ADS)
Dodin, A. V.; Lamzin, S. A.; Sitnova, T. M.
Using LTE calculations of the structure of T Tauri stellar atmospheres heated by radiation from an accretion shock (Dodin and Lamzin 2012), we have calculated the spectrum of the hot spot emerging on the stellar surface by taking into account non-LTE effects for He I, He II, Ca I, and Ca II. Assuming the pre-shock gas density N 0 and velocity V 0 to be the same at all points of the accretion stream cross section, we have calculated the spectrum of the star+circular spot system at various N 0, V 0, and parameters characterizing the star and the spot. Using nine stars as an example, we show that the theoretical optical spectra reproduce well the observed veiling of photospheric absorption lines as well as the profiles and intensities of the so-called narrow components of He II and Ca I emission lines with an appropriate choice of parameters. The accreted gas density in all of the investigated stars except DK Tau has been found to be N 0 > 1012 cm-3. We have managed to choose the parameters for eight stars at a calcium abundance in the accreted gas ? Ca equal to the solar one, but we have been able to achieve agreement between the calculations and observations for TW Hya only by assuming ? Ca to be approximately a factor of 3 lower than the solar one. The estimated parameters do not depend on interstellar extinction, because they have been determined from the spectra normalized to the continuum level. The calculated intensity of Ca II lines has turned out to be lower than the observed one, but this contradiction can be eliminated by assuming that, in addition to the accreted gas with a high density N 0, a more rarefied gas also falls onto the star. The theoretical equivalent widths and relative intensities of the subordinate He I lines disagree significantly with the observations. This is apparently because non-LTE effects should be taken into account when calculating the structure of the upper layers of the hot spot, the accuracy of the cross sections for collisional processes from upper levels is insufficient, and the spot inhomogeneity should probably be taken into account.
ClONO2 vertical profile and estimated mixing ratios of ClO and HOCl in winter Arctic stratosphere from Michelson interferometer for passive atmospheric sounding limb emission spectra
T. von Clarmann; G. Wetzel; H. Oelhaf; F. Friedl-Vallon; A. Linden; G. Maucher; M. Seefeldner; O. Trieschmann; F. Lef�vre
Nighttime limb emission spectra recorded by the balloon-borne Michelson interferometer for passive atmospheric sounding (MIPAS) on February 11, 1995, near Kiruna were used to infer a vertical profile of ClONO2 as well as estimates of ClO and HOCl volume mixing ratios. The highest ClONO2 mixing ratio [2.6 parts per billion by volume (ppbv)] was found at 22.69 km altitude and
Schnittman, Jeremy D. [NASA Goddard Space Flight Center Greenbelt, MD 20771 (United States); Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University Baltimore, MD 21218 (United States); Noble, Scott C., E-mail: email@example.com, E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Center for Computational Relativity and Gravitation, Rochester Institute of Technology Rochester, NY 14623 (United States)
We present the results of a new global radiation transport code coupled to a general relativistic magnetohydrodynamic simulation of an accreting, non-rotating black hole. For the first time, we are able to explain from first principles in a self-consistent way all the components seen in the X-ray spectra of stellar-mass black holes, including a thermal peak and all the features associated with strong hard X-ray emission: a power law extending to high energies, a Compton reflection hump, and a broad iron line. Varying only the mass accretion rate, we are able to reproduce a wide range of X-ray states seen in most galactic black hole sources. The temperature in the corona is T{sub e} {approx} 10 keV in a boundary layer near the disk and rises smoothly to T{sub e} {approx}> 100 keV in low-density regions far above the disk. Even as the disk's reflection edge varies from the horizon out to Almost-Equal-To 6M as the accretion rate decreases, we find that the shape of the Fe K{alpha} line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations.
Suzaku X-ray Spectra and Pulse Profile Variations during the Superorbital Cycle of LMC X-4
Hung, Li-Wei; Boroson, Bram; Vritlek, Saeqa D
We present results from spectral and temporal analyses of Suzaku and RXTE observations of the high mass X-ray binary LMC X-4. Using the full 13 years of available RXTE/ASM data, we apply the ANOVA and Lomb normalized Periodogram methods to obtain an improved superorbital period measurement of 30.32 +/- 0.04 days. The phase-averaged X-ray spectra from Suzaku observations during the high state of the superorbital period can be modeled in the 0.6--50 keV band as the combination of a power-law with Gamma ~ 0.6 and a high-energy cutoff at ~ 25 keV, a blackbody with kT_BB ~ 0.18 keV, and emission lines from Fe K_alpha, O VIII, and Ne IX (X Lyalpha). Assuming a distance of 50 kpc, The source has luminosity L_X ~ 3 x 10^38 ergs s^-1 in the 2--50 keV band, and the luminosity of the soft (blackbody) component is L_BB ~ 1.5 x 10^37 ergs s^-1. The energy resolved pulse profiles show single-peaked soft (0.5-1 keV) and hard (6-10 keV) pulses but a more complex pattern of medium (2-10 keV) pulses; cross-correlation of the h...
A newly discovered DLA and associated Ly? emission in the spectra of the gravitationally lensed quasar UM673A,B
NASA Astrophysics Data System (ADS)
Cooke, Ryan; Pettini, Max; Steidel, Charles C.; King, Lindsay J.; Rudie, Gwen C.; Rakic, Olivera
The sightline to the brighter member of the gravitationally lensed quasar pair UM673A,B intersects a damped Ly? system (DLA) at z = 1.62650 which, because of its low redshift, has not been recognized before. Our high-quality echelle spectra of the pair, obtained with HIRES on the Keck I telescope, show a drop in neutral hydrogen column density N(HI) by a factor of at least 400 between UM673A and UM673B, indicating that the DLA's extent in this direction is much less than the 2.7 h-170kpc separation between the two sightlines at z = 1.62650. By re-assessing this new case together with published data on other quasar pairs, we conclude that the typical size (radius) of DLAs at these redshifts is R ~= (5 +/- 3) h-170kpc, smaller than previously realized. Highly ionized gas associated with the DLA is more extended, as we find only small differences in the CIV absorption profiles between the two sightlines. Coincident with UM673B, we detect a weak and narrow Ly? emission line which we attribute to star formation activity at a rate SFR >~ 0.2Msolaryr-1. The DLA in UM673A is metal poor, with an overall metallicity ZDLA ~= 1/30Zsolar, and has a very low internal velocity dispersion. It exhibits some apparent peculiarities in its detailed chemical composition, with the elements Ti, Ni and Zn being deficient relative to Fe by factors of 2-3. The [Zn/Fe] ratio is lower than those measured in any other DLA or Galactic halo star, presumably reflecting somewhat unusual previous enrichment by stellar nucleosynthesis. We discuss the implications of these results for the nature of the galaxy hosting the DLA. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation. E-mail: email@example.com
Line emission from an accretion disk around black hole: effects of the disk structure
Vladimir I. Pariev; Benjamin C. Bromley
The observed iron K-alpha fluorescence lines in Seyfert galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. Previous studies of line emission have considered only geometrically thin disks, where the gas moves along geodesics in the equatorial plane of a black hole. Here we extend this work to include effects on line profiles from finite disk thickness, radial accretion flow and turbulence. We adopt the Novikov-Thorne solution, and find that within this framework, turbulent broadening is the most significant effect. The most prominent changes in the skewed, double-horned line profiles is a substantial reduction in the maximum flux at both red and blue peaks. We show that at the present level of signal-to-noise in X-ray spectra, proper treatment of the actual structure of the accretion disk can change estimates of the inclination angle of the disk. Thus these effects will be important for future detailed modeling of high quality observational data.
Continuum Fitting HST QSO Spectra
NASA Technical Reports Server (NTRS)
Tytler, David; Oliversen, Ronald J. (Technical Monitor)
The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.
Probing dynamics in the Franck-Condon and exit channel regions of dissociating H2S: Emission spectra upon tunable excitation
Butler, Laurie J.
, and L. J. Butler The James Franck Institute and Department of Chemistry, The Universi@ of ChicagoProbing dynamics in the Franck-Condon and exit channel regions of dissociating H2S: Emission,S at excitation energies near 200 nm to probe the dissociation dynamics from a conical intersection in the Franck
A calculation of the neutron emission spectra and the neutron number produced by (p, n) reaction for some thick targets composed of heavy elements from 0.5 GeV to 3.0 GeV
NASA Astrophysics Data System (ADS)
Thu, Nguyen Thi Ai; Mong Giao, Nguyen
The calculation of neutron multiplicity and its energy spectra in (p,n) reactions are very important and necessary for designing and manufacturing the target for an Accelerator Driven System (ADS). The neutron multiplicity in (p,n) reactions on different thin targets with different proton beam energies has been presented in the JENDL-HE library. However, the target used in the ADS must be thick so that the number of neutrons produced is as large as possible. For this reason, we can't directly use the results in the JENDL-HE library. In this paper, we calculate neutron emission spectra and multiplicity in (p,n) reactions for some thick target nuclei including Pb204, Pb206, Pb207, Pb208, W180, W182 W184 W186, U235, U238, Au197 with proton beam energies ranging from 0.5 GeV to 3.0 GeV.
Ab initio potential energy surfaces for both the ground (X (1)A') and excited (A (1)A") electronic states of HGeCl and the absorption and emission spectra of HGeCl/DGeCl.
Lin, Sen; Xie, Daiqian; Guo, Hua
Potential energy surfaces for the ground (X (1)A(')) and excited (A (1)A(")) electronic states of HGeCl and the transition dipole moment surface were obtained using an internally contracted multireference configuration interaction method with the Davidson correction and an augmented correlation-consistent polarized valence quadruple zeta basis set. Calculated vibrational energy levels of HGeCl and DGeCl on both the ground and excited electronic states are in excellent agreement with available experimental data. In addition, the absorption and emission spectra of both HGeCl and DGeCl were obtained using an efficient single Lanczos propagation method and the agreement with experimental spectra is also excellent. PMID:19045199
Lipid raft facilitated ligation of K-{alpha}1-tubulin by specific antibodies on epithelial cells: Role in pathogenesis of chronic rejection following human lung transplantation
Tiriveedhi, Venkataswarup; Angaswamy, Nataraju [Department of Surgery, Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (United States)] [Department of Surgery, Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (United States); Weber, Joseph [Department of Medicine, Washington University School of Medicine, St. Louis, MO (United States)] [Department of Medicine, Washington University School of Medicine, St. Louis, MO (United States); Mohanakumar, T., E-mail: firstname.lastname@example.com [Department of Surgery, Pathology and Immunology, Washington University School of Medicine, St. Louis, MO (United States)
Research highlights: {yields} Addition of KAT Abs (+) sera to NHBE culture causes upregulation of growth factors. {yields} Cholesterol depletion causes down regulation of growth factor expression. {yields} Cholesterol depletion is accompanied by loss of membrane bound caveolin. {yields} Thus, we demonstrate lipid raft are critical for efficient ligation of the KAT Abs. -- Abstract: Long term function of human lung allografts is hindered by development of chronic rejection manifested as Bronchiolitis Obliterans Syndrome (BOS). We have previously identified the development of antibodies (Abs) following lung transplantation to K-{alpha}1-tubulin (KAT), an epithelial surface gap junction cytoskeletal protein, in patients who develop BOS. However, the biochemical and molecular basis of the interactions and signaling cascades mediated by KAT Abs are yet to be defined. In this report, we investigated the biophysical basis of the epithelial cell membrane surface interaction between KAT and its specific Abs. Towards this, we analyzed the role of the lipid raft-domains in the membrane interactions which lead to cell signaling and ultimately increased growth factor expression. Normal human bronchial epithelial (NHBE) cells, upon specific ligation with Abs to KAT obtained either from the serum of BOS(+) patients or monoclonal KAT Abs, resulted in upregulation of growth factors VEGF, PDGF, and bFGF (6.4 {+-} 1.1-, 3.2 {+-} 0.9-, and 3.4 {+-} 1.1-fold increase, respectively) all of which are important in the pathogenesis of BOS. To define the role for lipid raft in augmenting surface interactions, we analyzed the changes in the growth factor expression pattern upon depletion and enrichment with lipid raft following the ligation of the epithelial cell membranes with Abs specific for KAT. NHBE cells cultured in the presence of {beta}-methyl cyclodextran ({beta}MCD) had significantly reduced growth factor expression (1.3 {+-} 0.3, vs {beta}MCD untreated being 6.4 {+-} 1.1-fold increase) upon stimulation with KAT Abs. Depletion of cholesterol on NHBE cells upon treatment with {beta}MCD also resulted in decreased partitioning of caveolin in the membrane fraction indicating a decrease in raft-domains. In conclusion, our results demonstrate an important role for lipid raft-mediated ligation of Abs to KAT on the epithelial cell membrane, which results in the upregulation of growth factor cascades involved in the pathogenesis of BOS following human lung transplantation.
Interpretations of XeI and XeBr bound--free emission spectra and reactive quenching of Xe(/sup 3/P/sub 2/) atoms by bromine and iodine containing molecules
Tamagake, K.; Setser, D.W.; Kolts, J.H.
The XeBr and XeI emissions spectra have been recorded in a flowing afterglow apparatus from the reaction of Xe(/sup 3/P/sub 2/) atoms with 16 bromine and iodine containing reagents. In all cases both the B and C states of XeI and XeBr are observed; the inital B/C ratio is approx.1.5. The ratio increase with pressure because of collisional transfer from C to B. Comparison of the total XeBr and XeI emission intensities with the XeC1 emission intensity from Xe(/sup 3/P/sub 2/)+C1/sub 2/ is used to obtain rate constants for XeBr and XeI formation. The branching fractions for XeI and XeBr formation are large, probably unity, for Br/sub 2/, I/sub 2/, IC1, and IBr and relatively small for the polyatomic molecules except for CF/sub 3/I and possible CBr/sub 4/. From the short wavelength limit of the B--X spectra, upper limits to D/sub 0/(R--Br) and D/sub 0/(R--I) are assigned. The theoretical potential curves calculated by Dunning and Hay for the A, B, C, and X states of XeI and XeBr were slightly adjusted so that good agreement was obtained between the simulated and experimental spectra from low vibrational levels of the B and C states. These adjusted potential curves were used to simulate the spectra from high levels of XeBr and XeI, and initial XeBr and XeI vibrational distributions were assigned from matching the low pressure spectra. A systematic decrease in
Log-parabolic spectra and particle acceleration in blazars. III: SSC emission in the TeV band from Mkn 501
Massaro, E; Perri, M; Giommi, P; Tosti, G
Curved broad-band spectral distributions of non-thermal sources like blazars are described well by a log-parabolic (LP) law where the second degree term measures the curvature. LP energy spectra can be obtained for relativistic electrons by means of a statistical acceleration mechanism whose probability of acceleration depends on energy. In this paper we compute the spectra radiated by an electron population via synchrotron (S) and Synchro-Self Compton(SSC) processes to derive the relations between the LP parameters. These spectra were obtained by means of an accurate numerical code. We found that the ratio between the curvature parameters of the S spectrum to that of the electrons is equal to about 0.2 instead of 0.25, the value foreseen in the delta approximation. Inverse Compton spectra are also intrinsically curved and can be approximated by a log-parabola only in limited ranges. The curvature parameter, estimated around the SED peak, may vary from a lower value than that of the S spectrum up to that of e...
Studies of electronic configurations in the emission spectra of lanthanides and actinides: application to the interpretation of Es I and Es II, predictions for Fm I
Wyart, Jean-Francois [Laboratoire Aime Cotton, CNRS, Batiment 505, Centre Universitaire, FR-91405 Orsay Cedex (France)]. E-mail: email@example.com; Blaise, Jean [Laboratoire Aime Cotton, CNRS, Batiment 505, Centre Universitaire, FR-91405 Orsay Cedex (France); Worden, Earl F. [Physics and Advanced Technologies Directorate, Lawrence Livermore National Laboratory, L-044, Livermore, CA 94550 (United States)
The interpretation of the spectra of free atoms and gaseous ions in the 4f{sup N} and 5f{sup N} periods became less active after critical compilations of energy levels appeared. However, several spectra are still under study and the application of the Racah-Slater and HFR methods to extended sets of configurations leads to revisions and additions. In doubly charged ions of lanthanides, the treatment of configuration interaction by means of effective parameters and by extension of the basis of states are both important. Concerning actinides, calculations of several observables (Lande factors and isotope shifts in Pu I, hyperfine constants, transition probabilities) prove the quality of eigenfunctions. The classification of Es I and Es II has been extended and radial parameters for fine and hyperfine structures have been derived. Level predictions for the next element fermium are supported by parameter extrapolations.
Direct-potential-fit analysis of new infrared and UV\\/visible A 1?+-X 1?+ emission spectra of AgH and AgD
Robert J. Le Roy; Dominique R. T. Appadoo; Kevin Anderson; Alireza Shayesteh; Iouli E. Gordon; Peter F. Bernath
New high-resolution infrared and UV\\/visible spectra of 107AgH, 109AgH, 107AgD, and 109AgD have been recorded with a Fourier transform spectrometer. The new line positions are combined with published microwave and older electronic A 1?+-X 1?+ data and used, first in a decoupled analysis of the X state alone, and then in a global multi-isotopologue analysis which yields comprehensive descriptions of
Cackett, E. M.
While iron emission lines are well studied in black hole systems, both in X-ray binaries and active galactic nuclei, there has been less of a focus on these lines in neutron star low-mass X-ray binaries (LMXBs). However, ...
NSDL National Science Digital Library
Nave, Carl R.
This page from Hyperphysics contains images depicting the light emitted by several elements and their respective spectra. The page also provides a description of how the size of a holographic image scales with the wavelength of the light used to observe it.
The observable effect of a photospheric component on GRB�s prompt emission spectrum: peak energy clustering and flat spectra above the thermal peak
Asaf Pe�er; Peter Me�sza�ros; Martin J. Rees
A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRB�s) and X-ray flashes (XRF�s). We study the properties of plasmas containing a low energy thermal photon component at comoving temperature ? ? kT ? \\/ mec2 ? 10?5 � 10?2 interacting with an energetic electron component. We show that, for scattering
The observable effect of a photospheric component on GRB's prompt emission spectrum: peak energy clustering and flat spectra above the thermal peak
Asaf Pe'Er; Peter M�sz�ros; Martin J. Rees
A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRB's) and X-ray flashes (XRF's). We study the properties of plasmas containing a low energy thermal photon component at comoving temperature theta ? kT ' \\/ mec2 ~ 10-5 - 10-2 interacting with an energetic electron component. We show that, for scattering
Exploratory analysis of excitation-emission matrix fluorescence spectra with self-organizing maps as a basis for determination of organic matter removal efficiency at water treatment works
Magdalena Bieroza; Andy Baker; John Bridgeman
In the paper, the self-organizing map (SOM) was employed for the exploratory analysis of fluorescence excitation-emission data characterizing organic matter removal efficiency at 16 water treatment works in the UK. Fluorescence spectroscopy was used to assess organic matter removal efficiency between raw and partially treated (clarified) water to provide an indication of the potential for disinfection by-products formation. Fluorescence spectroscopy
A search for iron emission lines in the Chandra X-ray spectra of neutron star low-mass X-ray binaries
E. M. Cackett; J. M. Miller; J. Homan; M. van der Klis; W. H. G. Lewin; M. Mendez; J. Raymond; D. Steeghs; R. Wijnands
While iron emission lines are well studied in black hole systems, both in X-ray binaries and Active Galactic Nuclei, there has been less of a focus on these lines in neutron star low-mass X-ray binaries (LMXBs). However, recent observations with Suzaku and XMM-Newton have revealed broad asymmetric iron line profiles in 4 neutron star LMXBs, confirming an inner disk origin for these lines in neutron star systems. Here, we present a search for iron lines in 6 neutron star LMXBs. For each object we have simultaneous Chandra and RXTE observations at 2 separate epochs, allowing for both a high resolution spectrum, as well as broadband spectral coverage. Out of the six objects in the survey, we only find significant iron lines in two of the objects, GX 17+2 and GX 349+2. However, we cannot rule out that there are weak, broad lines present in the other sources. The equivalent width of the line in GX 17+2 is consistent between the 2 epochs, while in GX 349+2 the line equivalent width increases by a factor of ~3 between epochs as the source flux decreases by a factor of 1.3. This suggests that the disk is highly ionized, and the line is dominated by recombination emission. We find that there appears to be no specific locations in the long-term hardness-intensity diagrams where iron emission lines are formed, though more sources and further observations are required.
[Fluorescence spectra and absorption spectra of carvacrol].
Li, Li-Ran; Liu, Cui-Ge; Wei, Yong-Ju
Fluorescence spectra and absorption spectra of carvacrol, an active component of Chinese herbal medicines, have been studied. The ionization constant and fluorescence quantum yield of carvacrol were measured according to spectral data. Under the condition of pH < 2.0, fluorescence intensity of carvacrol increases with the increase in pH value. In the range of pH 2.0-8.0, carvacrol gives a strong and steady fluorescence with maximum excitation wavelength 278 nm and emission wavelength 306 nm. When pH > 8.0, the fluorescence intensity decreases with the increase in pH value. Ionization constant of carvacrol was measured to be pK(a) = 10.44 +/- 0.06 using a pH-absorbance method; and pK(a) = 10.40 +/- 0.04 using a pH-fluorescence method. Fluorescence intensity of carvacrol was remarkably enhanced when methanol was added into its aqueous solution. Using L-tryptophane as a reference, the fluorescence quantum yield of carvacrol aqueous solution was measured to be 0.121 at excitation wavelength 278 nm; while in a solution containing 80% methanol, the quantum yield was measured to be 0.324. PMID:22250552
Co-spatial Long-slit UV/Optical Spectra of Ten Galactic Planetary Nebulae with HST/STIS I. Description of the Observations, Global Emission-line Measurements, and CNO Abundances
Dufour, Reginald J; Shaw, Richard A; Henry, Richard B C; Balick, Bruce; Corradi, Romano L M
We present observations and initial analysis from an HST/STIS program to obtain the first co-spatial, UV-optical spectra of ten Galactic planetary nebulae (PNe). Our primary objective was to measure the critical emission lines of carbon and nitrogen with unprecedented S/N and spatial resolution over UV-optical range, with the ultimate goal of quantifying the production of these elements in low- and intermediate-mass stars. Our sample was selected from PNe with a near-solar metallicity, but spanning a broad range in N/O. This study, the first of a series, concentrates on the observations and emission-line measurements obtained by integrating along the entire spatial extent of the slit. We derived ionic and total elemental abundances for the seven PNe with the strongest UV line detections (IC~2165, IC~3568, NGC~2440, NGC~3242, NGC~5315, NGC~5882, and NGC~7662). We compare these new results with other recent studies of the nebulae, and discuss the relative merits of deriving the total elemental abundances of C, ...
Firefly luciferase has two nucleotide binding sites: effect of nucleoside monophosphate and CoA on the light-emission spectra.
Steghens, J P; Min, K L; Bernengo, J C
A laboratory-made spectroluminometer was used to analyse the light emitted by firefly (Photinus pyralis) luciferase reacting with several nucleotide derivatives. The analysis of the light emission in the presence of ATP or dATP provides some evidence that the enzyme has two nucleotide binding sites, each one leading to the formation of a complex emitting mainly at 575 nm (ATP) or 610 nm (dATP). AMP is able to displace dATP from the second site (610 nm) to the first one. Photoaffinity labelling of the second site by 8-azido-AMP gives similar results. The amplification effect of CoA and acetyl-CoA is also reconsidered according to this model. PMID:9806891
High resolution emission Fourier transform infrared spectra of the 4p-5s and 5p-6s bands of ArH
NASA Astrophysics Data System (ADS)
Baskakov, O. I.; Civi�, S.; Kawaguchi, K.
In the 2500-8500cm-1 region several strong emission bands of ArH40 were observed by Fourier transform spectroscopy through a dc glow discharge in a mixture of argon and hydrogen. Rotational-electronic transitions of the two previously unstudied 4p-5s and 5p-6s,v=0-0, bands of ArH40 were measured and assigned in the 6060 and 3770cm-1 regions, respectively. A simultaneous fit of the emission transitions of the 4p-5s and 5p-6s bands and an extended set of transitions of the 6s-4p band observed by Dabrowski, Tokaryk, and Watson [J. Mol. Spectrosc. 189, 95 (1998)] and remeasured in the present work yielded consistent values of the spectroscopic parameters of the electronic states under investigation. In the branch of the 4p-5s band with transitions of type Qf3eQ we observed a narrowing in the linewidths with increasing rotational quantum number N. The rotational dependence of the linewidth is caused by predissociation of the 5s state by the repulsive ground 4s state through homogeneous coupling and changes in overlap integrals of the vibrational wave functions with the rotational level. Analysis was based on the Fermi's golden rule approximation model. In the 4p-5s band region a vibrational sequence ofv'-v?=1-1, 2-2, and 3-3 were recorded and a number of transitions belonging to the strongest Qf3eQ form branch of the 1-1 band were analyzed.
Detailed non-LTE calculations of the iron emission from NGC 1068
NASA Technical Reports Server (NTRS)
Band, David L.; Klein, Richard I.; Castor, John I.; Nash, J. K.
The X-ray iron line emission from NGC 1068 observed by the Ginga satellite is modeled using the new multiline, multilevel, non-LTE radiative transport code ALTAIR and a detailed atomic model for Ne-like through stripped iron. The parameter space of the obscured type 1 Seyfert nucleus model for this object is studied. The equivalent width is greater than previously predicted. It is found that detailed radiative transfer can have a significant effect on the observed line flux both for the K alpha line and for the L-shell emission. The ionization of the iron increases with temperature. Therefore the K alpha equivalent width and energy is a function not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGC 1068 it is found that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance.
Theoretical spectra of terrestrial exoplanet surfaces
Hu, Renyu
We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable ...
Tracking variations in fluorescent-dissolved organic matter in an aerobic submerged membrane bioreactor using excitation-emission matrix spectra combined with parallel factor analysis.
Hur, Jin; Shin, Jaewon; Kang, Minsun; Cho, Jinwoo
In this study, the variations in the fluorescent components of dissolved organic matter (DOM) were tracked for an aerobic submerged membrane bioreactor (MBR) at three different operation stages (cake layer formation, condensation, and after cleaning). The fluorescent DOM was characterized using excitation-emission matrix (EEM) spectroscopy combined with parallel factor analysis (PARAFAC). Non-aromatic carbon structures appear to be actively involved in the membrane fouling for the cake layer formation stage as revealed by much higher UV-absorbing DOM per organic carbon found in the effluent versus those inside the reactor. Four fluorescent components were successfully identified from the reactor and the effluent DOMs by EEM-PARAFAC modeling. Among those in the reactor, microbial humic-like fluorescence was the most abundant component at the cake layer formation stage and tryptophan-like fluorescence at the condensation stage. In contrast to the reactor, relatively similar composition of the PARAFAC components was exhibited for the effluent at all three stages. Tryptophan-like fluorescence displayed the largest difference between the reactor and the effluent, suggesting that this component could be a good tracer for membrane fouling. It appears that the fluorescent DOM was involved in membrane fouling by cake layer formation rather than by internal pore adsorption because its difference between the reactor and the effluent was the highest among all the four components, even after the membrane cleaning. Our study provided an insight into the fate and the behavior fluorescent DOM components for an MBR system, which could be an indicator of the membrane fouling. PMID:24390578
High K-alpha X-ray Conversion Efficiency From Extended Source Gas Jet Targets Irradiated by Ultra Short Laser Pulses
Kugland, N L; Constantin, C; Collette, A; Dewald, E; Froula, D; Glenzer, S H; Kritcher, A; Neumayer, P; Ross, J S; Niemann, C
The absolute laser conversion efficiency to K{sub {alpha}}-like inner shell x-rays (integrated from K{sub {alpha}} to K{sub {beta}}) is observed to be an order of magnitude higher in argon gas jets than in solid targets due to enhanced emission from higher ionization stages following ultra short pulse laser irradiation. Excluding the higher ionization stages, the conversion efficiency to near-cold K{sub {alpha}} is the same in gas jets as in solid targets. These results demonstrate that gas jet targets are bright, high conversion efficiency, high repetition rate, debris-free multi-keV x-ray sources for spectrally resolved scattering and backlighting of rapidly evolving dense matter.
NASA Astrophysics Data System (ADS)
Wills, B. J.; Brotherton, M. S.
QSOs' emission lines arise from highest velocity (approximately 10000 km/s), dense gas within approximately 0.1 parsec of the central engine, out to low-velocity, low-density gas at great distances from the host galaxy. In radio-loud QSOs there are clear indications that the distribution and kinematics of emission-line gas are related to the symmetry axis of the central engine, as defined by the radio jet. These jets originate at nuclear distances < 0.1 pc --- similar to the highest-velocity emission line gas. There are two ways we can investigate the different environments of radio-loud and radio-quiet QSOs, i.e., those with and without powerful radio jets. One is to look for optical-UV spectroscopic differences between radio-loud and radio-quiet QSOs. The other is to investigate dependences of spectroscopic properties on properties of the powerful jets in radio-loud QSOs. Here we summarize the spectroscopic differences between the two classes, and present known dependences of spectra on radio core-dominance, which we interpret as dependences on the angle of the central engine to the line-of-sight. We speculate on what some of the differences may mean.
Thermal infrared spectra of the Moon
NASA Technical Reports Server (NTRS)
Salisbury, John W.; Murcray, D. G.; Williams, W. J.; Blatherwick, R. D.
Contrary to recent assertions in the literature, lunar emission spectra obtained at an altitude of 32 km with a balloon-borne telescope are virtually undistorted by atmospheric absorption, except in the ozone region. These spectra have been found to correlate closely with laboratory emission spectra of returned lunar samples measured in a simulated lunar environment. Thus, lunar spectra obtained with the balloon-borne telescope system are the standards against which groundbased spectral measurements of the Moon should be compared. Comparison of balloon-borne measurements with recent groundbased spectral measurements suggests that the latter suffer from some source of systematic error. When high-quality lunar spectra are available, they will be best interpreted by comparison with returned lunar samples, rather than terrestrial minerals or rocks, because of subtle spectral differences between lunar and terrestrial minerals perhaps associated with incipient alteration of the latter.
Collum, David B.
S16 1 H and 13 C NMR Spectra (see p S3) Me N-i-Pr #12;S17 1 H and 13 C NMR Spectra (see p S3) Me NBn #12;S18 1 H and 13 C NMR Spectra (see p S4) NBn #12;S19 1 H and 13 C NMR Spectra (see p S4) NBn Me Me Me #12;S20 1 H and 13 C NMR Spectra (see p S4) N-n-Bu Me Me Me #12;S21 1 H and 13 C NMR Spectra
Mid-Infrared Spectra of Be Stars
S. A. Rinehart; J. R. Houck; J. D. Smith
We present the first medium-resolution ($R\\sim 600$) mid-infrared (8-13.3\\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $\\gamma$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two of the sources, $\\beta$ Lyr and MWC 349 also show emission from other species. Both of these objects show evidence of [Ne II] emission, and $\\beta$ Lyr also shows evidence of He I emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.
Detailed non-LTE calculations of the iron emission from NGC 1068
Band, D.L.; Klein, R.I.; Castor, J.I.; Nash, J.K.
We model the x-ray iron line emission from NGC 1068 observed by the Ginga satellite using the new multi-line, multi-level, non-LTE radiative transport code ALTAIR and a detailed atomic model for Ne-like through stripped iron. With these detailed calculations we study the parameter space of the obscured type 1 Seyfert nucleus'' model for this object. We find that the equivalent width is greater than previously predicted because the observed K{alpha} line is produced not only by fluorescence but also by scattering of the continuum into our line of sight by the line opacity. We find that detailed radiative transfer can have a significant effect on the observed line flux both for the K{alpha} line and for the L-shell emission. The ionization of the iron increases with temperature. Therefore the K{alpha} equivalent width and energy is a function not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGG 1068 we find that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance. 17 refs., 6 figs.
Iron Fluorescent Line Emission from Black Hole Accretion Disks with Magnetic Reconnection-Heated Corona
N. Kawanaka; S. Mineshige; K. Iwasawa
We investigate the iron K$\\alpha$ fluorescent line produced by hard X-ray photons from magnetic reconnection-heated corona. The hot corona with temperature being about $10^9$K can irradiate the underlying disk with a continuum X-ray spectrum produced via thermal Comptonization. Then the iron atoms in the disk photoelectrically absorb X-ray photons and radiate K$\\alpha$ line photons. Therefore, the activity of corona is responsible to the iron line emission from the underlying disk. In previous studies, oversimplified X-ray photon sources are often assumed above the disk in order to compute the iron line profile or power-law line emissivity profiles are assumed with an index being a free parameter. We adopt the more realistic corona model constructed by Liu et al. in which the corona is heated by magnetic energy released through the reconnection of magnetic flux loops and which has no free parameter. Then the accretion energy is dominantly dissipated in the corona, in which X-ray photons are efficiently produced and irradiate the underlying disk. We find the local emmisivity of iron line on the disk is approximated as $F_{{\\rm K}\\alpha}(r)\\propto r^{-5}$. The iron line profiles derived from this model give excellent fits to the observational data of MCG-6-30-15 with the profiles derived theoretically for $i\\sim 30^{\\circ}$ for energy band 4-7keV. Possible origins of line variability are briefly discussed.
NSDL National Science Digital Library
Zollman, Dean
This resource, part of the Spectroscopy Lab Suite, simulates optical transitions in gasses. Spectra from gas emission tubes are shown, along with an interactive tool for students to create bound state energy levels and electronic transitions to match the observed spectra.
G. H. Dieke; H. M. Crosswhite
The present status of the knowledge of the structure of the spectra of ; the doubly and triply ionized spectra of the rare earths is derived partly from ; experimental data of the emission spectra of the free ions which provide the ; energy level scheme in great detail but are difficuit and laborious to analyze. ; For the lower
Digital filtering of plume emission spectra
NASA Technical Reports Server (NTRS)
Madzsar, George C.
Fourier transformation and digital filtering techniques were used to separate the superpositioned spectral phenomena observed in the exhaust plumes of liquid propellant rocket engines. Space shuttle main engine (SSME) spectral data were used to show that extraction of spectral lines in the spatial frequency domain does not introduce error, and extraction of the background continuum introduces only minimal error. Error introduced during band extraction could not be quantified due to poor spectrometer resolution. Based on the atomic and molecular species found in the SSME plume, it was determined that spectrometer resolution must be 0.03 nm for SSME plume spectral monitoring.
Ultraviolet stellar spectra obtained on Skylab
NASA Technical Reports Server (NTRS)
Henize, K. G.; Wray, J. D.; Parsons, S. B.; Benedict, G. F.
A 15-cm aperture f/3 Ritchey-Chretien telescope equipped with a 4 deg calcium fluoride prism was employed in taking objective prism spectra from 1300 to 5000 A in 188 stars, in the three Skylab missions. Spectra of 2 A resolution at 1400 A and 10 A at 2000 A, extending to B0 stars such that V equals 6.5, were taken of 400 stars in the neighborhood of 1500 A. Stellar temperature and luminosity variations are revealed in resonance lines of C IV and Si IV. Profiles of P Cygni type show up in the spectra of all stars with absolute bolometric magnitudes brighter than minus 8.4, implying appreciable outflow of mass. Spectra with emission lines shortward of 2000 A were obtained for 12 WR stars, and spectra of some companion stars dominating the UV spectra are reported.
The effect of covariance between the K alpha and the K beta lead peak concentrations on the uncertainty in the result of in vivo (109)Cd KXRF bone lead measurement.
Brito, J A A
The effect of covariance between the K alpha and K beta lead peak concentrations on the uncertainty in the (109)Cd K x-ray fluorescence measurement of lead in bone is addressed here. It is commonly believed that this covariance arises as a result of the mutual dependence of the ratios of x-ray to coherent amplitudes on the same coherent peak amplitude. Previous work assumes statistical independence between spectral quantities of interest, crudely estimates the uncertainties in the lead peak concentrations, and suggests that the effect of covariance on the measurement uncertainty is small and can be ignored. Consequently, the current method followed by most laboratories reports the measurement uncertainty as if the fluctuations in the measured peak concentrations were independent. The robustness of such assumption, however, is undermined by existing epidemiological data. This paper assesses the magnitude of the covariance effect, using a method based on the observed significant correlations between the ratios of x-ray to coherent peak amplitudes in series of repeat phantom measurements. The revised uncertainties following this approach can exceed the uncertainties estimated by the accepted method by as much as 40%, which suggests a much stronger effect of covariance on the measurement uncertainty than previously reported. PMID:17110775
Interpretation of the auger electron spectra (AES) of sulfide minerals
David J. Vaughan; John A. Tossell
Auger electron spectra (AES) of sulfides are interpreted using published photoelectron spectra, sulfurK� X-ray emission spectra (XES) and Multiple ScatteringXa calculations on metal-sulfide molecular clusters and using newly measured spectra for ZnS, Cu2S and MoS2. For compounds without appreciable metald-sulfur 3p interactions, only one sulfur LVV peak or a closely spaced doublet is observed. For those with substantial metald-sulfur 3p
Selection and Characterization of Interesting Grism Spectra
G. R. Meurer
Observations with the ACS Wide Field Camera and G800L grism can produce thousands of spectra within a single WFC field producing a potentially rich treasure trove of information. However, the data are complicated to deal with. Here we describe algorithms to find and characterize spectra of emission line galaxies and supernovae using tools we have developed in conjunction with off the shelf software.
Garcia, J. [IACS, Physics Department, Catholic University of America, Washington DC 20064 (United States); Kallman, T. R., E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
We present new models for illuminated accretion disks, their structure, and reprocessed emission. We consider the effects of incident X-rays on the surface of an accretion disk by simultaneously solving the equations of radiative transfer, energy balance, and ionization equilibrium over a large range of column densities. We assume plane-parallel geometry and azimuthal symmetry, such that each calculation corresponds to a ring at a given distance from the central object. Our models include recent and complete atomic data for K-shell processes of the iron and oxygen isonuclear sequences. We examine the effect on the spectrum of fluorescent K{alpha} line emission and absorption in the emitted spectrum. We also explore the dependence of the spectrum on the strength of the incident X-rays and other input parameters, and discuss the importance of Comptonization on the emitted spectrum.
X-ray Emission from the Host Clusters of Powerful AGN
Patrick B. Hall; Erica Ellingson; Richard F. Green
(Abridged) We report the detection of X-ray emission from the host cluster of the radio-quiet quasar H1821+643 with the ROSAT HRI, and the non-detection of the host cluster of the radio-loud quasar 3C206 using the EINSTEIN HRI. CL1821+643 has a rest-frame 0.1-2.4 keV luminosity of 3.74$\\pm$0.57 h$_{50}^{-2}$ 10^45 ergs/sec, 38% from a barely resolved cooling flow component, which places it among the most X-ray luminous clusters known. The cluster emission complicates interpretation of previous X-ray spectra of this field; in particular, the observed FeK$\\alpha$ emission can probably be attributed entirely to the cluster, and either the quasar is relatively X-ray quiet for its optical luminosity or the cluster has a relatively low temperature for its luminosity. We combine these data with the recent detection of X-ray emission from the host cluster of the `buried' radio-quiet quasar IRAS 09104+4109, our previous upper limits for the host clusters of two z$\\sim$0.7 RLQs, and literature data on FR II radio galaxies and compare to the predictions of three models for the presence and evolution of powerful AGN in clusters: the low-velocity-dispersion model, the low-ICM-density model, and the cooling flow model. Neither of the latter two models can explain all the observations. We suggest that strong interactions with gas-containing galaxies may be the only mechanism needed to explain the presence and evolution of powerful AGN in clusters, consistent with the far-IR and optical properties of the host galaxies studied here. However, the cooling flow model cannot be ruled out for at least some objects, and it is likely that both processes are at work. Each scenario makes predictions for future X-ray and optical observations which can test their relative importance.
Mid-infrared spectra of Martian komantiite
NASA Technical Reports Server (NTRS)
Reyes, David P.
Synthetic mid-infrared emissive spectra of basalts of possible Martian komatiitic compositions were generated to show what might be seen in data returned from the Thermal Emission Spectrometer (TES). TES is flying on the Mars Observer arriving at Mars in late 1993. The synthetic Martian komatiite spectra were generated using mineralogy based on Shergottite, Nakhlite, and Chassigny (SNC) meteorites and Viking X-Ray Fluorescence (XRF) data. These data sets provide strong evidence for the existence of ultramafic lavas on Mars, particularly lavas of komatiitic composition.
ERIC Educational Resources Information Center
Jacobs, Stephen
Presents the Night Spectra Quest, a pocket-sized chart that identifies in color the spectra of all the common night lights and has an integrally mounted, holographic diffraction grating to look through. (JRH)
Porphyrins XIII: Fluorescence spectra and quantum yields
Paul G. Seybold; Martin Gouterman
Fluorescence spectra, quantum yields, natural radiative lifetimes, and absorption oscillator strengths are reported for a number of porphyrins in benzene solution. Emission yields for free base, Mg-, and Zn-phthalocyanine in 1-chloronaphthalene solution are also reported. The phthalocyanines are considerably more fluorescent than the porphyrins, and this is attributed mainly to their shorter radiative lifetimes. The heavy atom effect on fluorescence
K-Shell Diagram and Hypersatellite Spectra of 4D Transition Elements
Diamant, R.; Kao, C.; Huotari, S.; Hamalainen, K.; Sharon, R.; Honkimaki, V.; Buslaps, T.; Deutsch, M.
The K-shell diagram (K{alpha}{sub 1,2} and K{beta}{sub 1,3}) and hypersatellite (HS) (K{sup h}{alpha}{sub 1,2}) spectra of Y, Zr, Mo, and Pd have been measured with high energy-resolution using photoexcitation by 90 keV synchrotron radiation. Comparison of the measured and ab initio calculated HS spectra demonstrates the importance of quantum electrodynamical (QED) effects for the HS spectra. Phenomenological fits of the measured spectra by Voigt functions yield accurate values for the shift of the HS from the diagram lines, the splitting of the HS lines, and their intensity ratio. Good agreement with theory was found for all quantities except for the intensity ratio, which is dominated by the intermediacy of the coupling of the angular momenta. The observed deviations imply that our current understanding of the variation of the coupling scheme from LS to jj across the periodic table may require some revision.
Correlation of molecular structure with fluorescence spectra in rare earth chelates. I.
NASA Technical Reports Server (NTRS)
Bjorklund, S.; Degnan, J.; Filipescu, N.; Mcavoy, N.
Rare earth chelates fluorescence spectra correlation with molecular structure, analyzing emission spectrum internal Stark splitting of tetramethylammonium tetrakis /dibenzoylmethido/europate microcrystals
Resonant Compton scattering and gamma-ray burst continuum spectra
NASA Technical Reports Server (NTRS)
Baring, M. G.
The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.
X-ray spectra of Hercules X-1. I - Iron line fluorescence from a subrelativistic shell
NASA Technical Reports Server (NTRS)
Pravdo, S. H.; Becker, R. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Swank, J. H.
The X-ray spectrum of Her X-1 was observed in the energy range from 2 to 24 keV from August 29 to September 3, 1975. Emission features are observed near the K-alpha iron-line energy which exhibit both broadening and a double line structure. The total luminosity in these features is about 4 by 10 to the 35th power ergs/s. Iron line fluorescence from an opaque cool (not exceeding 1 million K) shell of material at the Alfven surface provides the necessary luminosity in this feature. The double line structure and the line energy width can be due to Doppler shifts if the shell is forced to corotate with the pulsar at a radius of at least 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.
Stimulated emission from semiconductor microcavities
Fan, X.; Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)
Laser-like emissions from semiconductor microcavities at low temperature have attracted considerable attention recently because of the possibility of realizing a non-equilibrium condensate by using cavity-polaritons. In this paper the authors present experimental studies of optical properties of a microcavity near the lasing threshold. They show that the minimum lasing threshold is achieved when the cavity is tuned significantly below the exciton line center. By comparing emission spectra with reflectivity spectra, they also show that well-resolved doublet in the emission spectra near the lasing threshold are not associated with cavity-polaritons. These results suggest that laser-like emissions form the microcavity are due to conventional stimulated emission processes with exciton localization playing a significant role.
Tiernan, M.
Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.
High-energy thermal synchrotron emission
NASA Technical Reports Server (NTRS)
Imamura, J. N.; Epstein, R. I.; Petrosian, V.
It is shown how the thermal synchrotron emission spectrum is modified when the photon energy is greater than the mean energy of the radiating particles. The effect if applying this energy conservation constraint is to produce spectra which have less high-energy photon emission than had been previously estimated. The thermal synchrotron spectra provide satisfactory fits to recently observed very high energy gamma ray spectra of certain burst sources.
The analysis of spectra of novae taken near maximum
NASA Technical Reports Server (NTRS)
Stryker, L. L.; Hestand, J.; Starrfield, S.; Wehrse, R.; Hauschildt, P.; Spies, W.; Baschek, B.; Shaviv, G.
A project to analyze ultraviolet spectra of novae obtained at or near maximum optical light is presented. These spectra are characterized by a relatively cool continuum with superimposed permitted emission lines from ions such as Fe II, Mg II, and Si II. Spectra obtained late in the outburst show only emission lines from highly ionized species and in many cases these are forbidden lines. The ultraviolet data will be used with calculations of spherical, expanding, stellar atmospheres for novae to determine elemental abundances by spectral line synthesis. This method is extremely sensitive to the abundances and completely independent of the nebular analyses usually used to obtain novae abundances.
Brenneman, Laura W. [NASA's GSFC, Mail Code 662, Greenbelt, MD 20771 (United States); Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
We present a uniform X-ray spectral analysis of eight type-1 active galactic nuclei that have been previously observed with relativistically broadened iron emission lines. Utilizing data from the XMM-Newton European Photon Imaging Camera (EPIC-pn) we carefully model the spectral continuum, taking complex intrinsic absorption and emission into account. We then proceed to model the broad Fe K{alpha} feature in each source with two different accretion disk emission line codes, as well as a self-consistent, ionized accretion disk spectrum convolved with relativistic smearing from the inner disk. Comparing the results, we show that relativistic blurring of the disk emission is required to explain the spectrum in most sources, even when one models the full reflection spectrum from the photoionized disk.
V. Sidorov
The neutron spectra produced in the bombardment or V, Co, and Ni targets ; by alpha particles at 11 to 20 Mev are measured using the time-of-flight method. ; The analysis of these spectra according to the statistical theory of nuclear ; reactions is performed with an electronic computer. The level density fanction ; type that gives optimal agreement with
Martin Gouterman
The review opens by presenting the absorption spectra for three series of porphyrins derived from the basic skeleton: (a) compounds obtained by simple substitution; (b) compounds obtained by reduction of one or more pyrrole rings; and (c) compounds obtained from fusion of aromatic rings onto the basic skeleton. The spectra are discussed in terms of a four orbital model-that is
Alexei V. Filippenko
The temporal evolution of the optical spectra of various types of supernovae (SNe) is illustrated, in part to aid observers classifying supernova candidates. Type II SNe are defined by the presence of hydrogen, and they exhibit a very wide variety of photometric and spectroscopic properties. Among hydrogen-deficient SNe (Type I), three subclasses are now known: those whose early-time spectra show
Direct-potential-fit analysis of new infrared and UV\\/visible A 1Sigma+-X 1Sigma+ emission spectra of AgH and AgD
Robert J. Le Roy; Dominique R. T. Appadoo; Kevin Anderson; Alireza Shayesteh; Iouli E. Gordon; Peter F. Bernath
New high-resolution infrared and UV\\/visible spectra of 107AgH, 109AgH, 107AgD, and 109AgD have been recorded with a Fourier transform spectrometer. The new line positions are combined with published microwave and older electronic A 1Sigma+-X 1Sigma+ data and used, first in a decoupled analysis of the X state alone, and then in a global multi-isotopologue analysis which yields comprehensive descriptions of
Modeling AGN spectra with PHOENIX: a self-consistent approach
Darrin Casebeer; Edward A. Baron; David Branch; Karen Leighly
We find that spectra of certain Iron Low Ionization Broad Absorption Line (FeLOBAL) QSOs, which are characterized by low--ionization emission and blue shifted absorption lines, can be well matched with the spectral synthesis code SYNOW. SYNOW is a resonance scattering code and assumes that line emission comes from a single line forming region. This interpretation is novel as traditionally line emission and absorption in BALQSOs are thought to come from two different regions. We extend this analysis by using the detailed PHOENIX code to model the spectra. We present a SYNOW fit and a preliminary model result from PHOENIX.
Low energy X-ray spectra measured with a mercuric iodide energy dispersive spectrometer in a scanning electron microscope
NASA Technical Reports Server (NTRS)
Iwanczyk, J. S.; Dabrowski, A. J.; Huth, G. C.; Bradley, J. G.; Conley, J. M.
A mercuric iodide energy dispersive X-ray spectrometer, with Peltier cooling provided for the detector and input field effect transistor, has been developed and tested in a scanning electron microscope. X-ray spectra were obtained with the 15 keV electron beam. An energy resolution of 225 eV (FWHM) for Mn-K(alpha) at 5.9 keV and 195 eV (FWHM) for the Mg-K line at 1.25 keV has been measured. Overall system noise level was 175 eV (FWHM). The detector system characterization with a carbon target demonstrated good energy sensitivity at low energies and lack of significant spectral artifacts at higher energies.
NASA Technical Reports Server (NTRS)
The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.
Cathodoluminescence spectra of gallium nitride nanorods
Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720�C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896
8- to 13-micron spectra of asteroids
NASA Astrophysics Data System (ADS)
Green, S. F.; Eaton, N.; Aitken, D. K.; Roche, P. F.; Meadows, A. J.
It is pointed out that thermal emission from asteroids reaches a maximum in the 10- to 20-micron region. In connection with the present investigation, a uniform set of spectra was obtained in the 8- to 13-micron region for 12 asteroids (together with additional observations of 19 Fortuna). These spectra provide a potentially valuable data set for future use (e.g., with IRAS data). The main conclusion from the obtained results is that diagnostic emission features of the type observed by Feierberg et al. (1983) are not common in C- and M-type asteroids. Optical studies of 19 Fortuna do not reveal any unusual properties which distinguish it from other C-type asteroids observed.
HOTSPUR: gamma ray emission from spheres pulsed with D-T neutrons. I. Calibration of improved NE213 detector assembly. II. Comparison of TART/SANDYL electron recoil spectra to experiment; preliminary results
Goldberg, E.; Hansen, L.F.; Komoto, T.T.; Pohl, B.A.
The NE213 scintillator detector was modified so that the pulse height would be linear with electron energy over the full range of interest - up to 7.1 MeV. Absolute calibration was done with four different calibrated gamma sources. An average correction factor is obtained which normalizes SANDYL calculations with respect to the calibration experiments. The procedure for calculating neutron-induced gamma-ray output and electron recoil spectra is described, and experimental data from a number of spherical assemblies are given and compared to TART/SANDYL calculations. (LEW)
Thermodynamic analysis of spectra
NASA Astrophysics Data System (ADS)
Mitchell, G. E.; Shriner, J. F.
Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra�the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the ?3 statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic "internal energy" and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is ?3, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.
Mahinder S. Uberoi; Stanley Wallis
Energy spectra of the longitudinal and lateral turbulent velocities are measured behind grids of different geometries; the isotropic relation is not satisfied. Energy-dissipating eddies are more nearly isotropic than energy-containing eddies. Spectra of the energy-containing eddies and their deviation from isotropy depend on the grid geometry. Various microscales are measured to determine the anisotropy of the energy-dissipating eddies. The error
Stimulated emission in semiconductor quantum wire heterostructures
E. Kapon; D. M. Hwang; R. Bhat
We report the first observation of stimulated emission in quasi-one-dimensional semiconductor quantum wires. Amplified spontaneous emission and stimulated emission spectra of the GaAs\\/AlGaAs quantum wires exhibit fine structure arising from transitions between lateral, one-dimensional electron and hole subbands. The observed subband separations, ~10 meV, are consistent with the calculated ones.
Emission lines in the spectrum of VEGA
E. S. Barker; D. L. Lambert; J. Tomkin; J. Africano
High-resolution low-noise spectra of the OI and Ca II near-infrared lines in Vega were obtained in 1977 and 1978. The violet-shifted emission components discovered by Johnson and Wisniewski are not detected. The absence of the emission lines suggests that either Vega is a subtle variable or the emission lines were of instrumental origin.
Characterization of the first excited 1?1 and ground X 1?+ states of MgXe. II. Analysis of 1?1 ? X 1? + bound-free emission spectra
NASA Astrophysics Data System (ADS)
McCaffrey, John G.; Funk, David J.; Breckenridge, W. H.
Laser-induced fluorescence (LIF) measurements of the Mg(3s3p 1P1)?Xe(1?1) ?Mg(3s3s 1S0)?Xe(X 1?+) transition of the jet-cooled MgXe complex have revealed that the ground X 1?+ state is quite weakly bound (De` ? 100 cm-1) compared to the 1?1 excited state (De' ? 1500 cm-1), and that the bond length in the 1?1 excited state is some 1.5 � shorter. Here we report the observation of dispersed fluorescence spectra from single vibrational levels of the 1?1 state, consisting mainly of oscillatory bound-free continua which extend over some 7500 cm-1. These spectra are analyzed using the semiclassical method of Child and LeRoy to determine the repulsive portion of the Mg?Xe(X 1?+) interaction potential up to nearly 1 eV in energy. Attempts were made to fit the experimental potential curves to several simple analytical functions, with a two-term Buckingham-type function yielding the best representation. A comparison of the repulsive portion of the Mg?Xe(X 1?) potential curve with that of the analogous Na?Xe(X 2?) curve determined similarly by Zimmerman and co-workers shows that the Na?Xe curve is even less repulsive than the Mg?Xe curve, even though the Mg?Xe potential is itself quite ``soft.'' This can be rationalized by the ability of the more diffuse Na(3s) electron to ``back-polarize'' (sp? hybridize) away from the Xe atom compared to the two Mg(3s2) electrons, thus reducing repulsion.
A p-type-doped quantum dot superluminescent LED with broadband and flat-topped emission spectra obtained by post-growth intermixing under a GaAs proximity cap.
Zhang, Z Y; Jiang, Q; Luxmoore, I J; Hogg, R A
Broadband superluminescent light emitting diodes are realized by a post-growth annealing process, on modulation p-doped multiple InAs/InGaAs/GaAs quantum dot layer structures, under a GaAs proximity cap. The device exhibits a large and flat emission with spectral width up to 132 nm at 2 mW. This is mainly attributed to the reduction of the energy separation between the ground state and the excited state, in addition to the optical quality of the intermixed modulation p-doped quantum dot materials being comparable to that of the as-grown sample. PMID:19417341
Disk-averaged synthetic spectra of Mars
NASA Technical Reports Server (NTRS)
Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather
The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.
Disk-averaged synthetic spectra of Mars.
Tinetti, Giovanna; Meadows, Victoria S; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather
The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin. PMID:16078866
Cassini UVIS observations of Titan nightglow spectra
NASA Astrophysics Data System (ADS)
Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd
In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 �) and FUV (1150-1900 �) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120� solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.
Measurements and parameterization of neutron energy spectra from targets bombarded with 120 GeV protons
NASA Astrophysics Data System (ADS)
Kajimoto, T.; Shigyo, N.; Sanami, T.; Iwamoto, Y.; Hagiwara, M.; Lee, H. S.; Soha, A.; Ramberg, E.; Coleman, R.; Jensen, D.; Leveling, A.; Mokhov, N. V.; Boehnlein, D.; Vaziri, K.; Sakamoto, Y.; Ishibashi, K.; Nakashima, H.
The energy spectra of neutrons were measured by a time-of-flight method for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000 MeV at emission angles of 30�, 45�, 120�, and 150�. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000 MeV calculated with PHITS code were 16-36% of the experimental yields and those calculated with FLUKA code were 26-57% of the experimental yields for all targets and emission angles.
Channeling effect in electronic spectra produced by grazing impact of fast protons on insulator surfaces
C. D. Archubi; M. S. Gravielle
Electron emission due to grazing scattering of fast protons from LiF and KCl surfaces is studied under axial incidence conditions. The differential emission probability is calculated within a distorted-wave formalism, taking into account axial channeled trajectories. For different emission angles, electronic spectra for proton incidence along the two principal crystal axes ([100] and [110]) are compared with those co rresponding
The angular power spectra of polarized Galactic synchrotron
M. Tucci; E. Carretti; S. Cecchini; R. Fabbri; M. Orsini; E. Pierpaoli
We derive the angular power spectra of intensity and polarization of Galactic synchrotron emission in the range 36 < l < 10^3 from the Parkes survey mapping the southern Galactic plane at 2.4 GHz. The polarization spectra of both electric and magnetic parity up to l \\simeq 10^3 are approximated very well by power laws with slope coefficients \\simeq 1.4, quite different from the CMB spectra. We show that no problem should arise from Galactic synchrotron for measurements of CMB polarization in the cosmological window.
Multibubble Sonoluminescence Spectra of Water which Resemble Single-Bubble Sonoluminescence
NASA Astrophysics Data System (ADS)
Didenko, Y. T.; Gordeychuk, T. V.
Multibubble sonoluminescence (MBSL) spectra of water from cavitation clouds were collected in the presence of different noble gases and at different acoustic intensities. Results show that at high acoustic intensity and with xenon as a dissolved gas the emission of the OH* radical becomes indiscernible from the continuum. These spectra resemble single-bubble sonoluminescence (SBSL) spectra. It is concluded that the source of emission in MBSL and SBSL can be the same, the difference in spectra is due to the higher temperature inside the bubble during SBSL.
Roux, St�phane; Jensen, Mogens H
The multifractal formalism characterizes the scaling properties of a physical density rho as a function of the distance L. To each singularity alpha of the field is attributed a fractal dimension for its support f(alpha). An alternative representation has been proposed by considering the distribution of distances associated to a fixed mass. Computing these spectra for a multifractal Cantor set, it is shown that these two approaches are dual to each other, and that both spectra as well as the moment scaling exponents are simply related. We apply the same inversion formalism to exponents obtained for turbulent statistics in the Gledzer-Ohkitani-Yamada shell model and observe that the same duality relation holds here. PMID:14995714
Montaudo, Maurizio S
Recent and older literature (covering the last 12-13 years) in the field of mass spectra of random and block copolymers is reviewed. A detailed description is given of the information on copolymer properties that can be recovered from the analysis of the low-mass region of the spectrum (the region below 500 Da) and the high-mass region. The features of mass spectra of copolymers obtained by different synthetic routes are discussed, such as free radical, condensation, ring-chain equilibration, microbial synthesis, ring-opening, simple anionic, cationic, Ziegler-Natta, and/or metallocene catalysis, along with some random and block copolymers that occur in Nature. The emphasis is on copolymer composition and average molar mass determination, and on the benefits of coupling mass spectrometry (MS) with separation techniques such as size-exclusion chromatography (SEC) and high performance liquid chromatography (HPLC). PMID:12373747
A. B. Kaidalov; V. A. Khoze; A. D. Martin; M. G. Ryskin
It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also briefly discuss the corresponding data for leading baryons produced in hadron-hadron collisions.
Fourier spectroscopy of the stratospheric emission
NASA Technical Reports Server (NTRS)
Carli, B.; Mencaraglia, F.; Bonetti, A.
Stratospheric emission spectra in the submillimeter range have been recorded with a resolution of 0.0033/cm with a balloon-borne interferometer. Several minor atmospheric constituents have been identified in a preliminary analysis of the spectra; these are water vapor, oxygen, ozone isotopes, nitric acid, nitrous oxide, hydrofluoric and hydrochloric acids, and carbon monoxide.
Retrieval of temperature profiles from Martian infrared spectra
NASA Technical Reports Server (NTRS)
Mcmillan, W. Wallace; Pearl, John C.; Conrath, Barney J.
In theory, a thermal emission spectrum of Mars (220-1600 cm(exp -1)) contains a wealth of information about the composition and thermal structure of the atmosphere and surface. However, in practice, the ability to retrieve quantitative information from the spectrum is limited by a number of factors including (1) the ill-posed nature of the spectral inversion problem and the resulting nonuniqueness of all solutions; (2) assumptions built into any spectral inversion program; (3) uncertainties in surface pressure, temperature, and emissivity; and (4) uncertainties in the optical properties of atmospheric aerosols. Below, factors (1) and (2) are discussed as fundamental limitations on temperature retrievals from Mariner 9 Infrared Interferometer Spectrometer (IRIS) spectra. In preparation for the Mars Observer mission and the return of tens of thousands of infrared spectra per day from the Thermal Emission Spectrometer (TES), we have developed a fast inversion algorithm to retrieve temperature structure and aerosol opacity from the infrared spectra. The derived atmospheric models will be used to provide the atmospheric contribution to the TES spectra, so that the thermal emission spectra of the underlying surface can be determined for making mineralogical identifications. As a test of our algorithm, we are undertaking a systematic analysis of the entire Mariner 9 Infrared Interferometric Spectrometer (IRIS) dataset of 21,000 plus spectra. While portions of the IRIS dataset have been previously analyzed, the lack of a speedy and robust algorithm to invert the IRIS spectra to retrieve temperature profiles and aerosol opacities has been a major impediment to a truly comprehensive analysis.
Infrared spectra of protostellar collapse
NASA Technical Reports Server (NTRS)
Hollenbach, David J.; Ceccarelli, Cecilia; Neufeld, David A.; Tielens, Alexander G. G. M.
Theoretical models of the formation of low mass stars by cloud collapse predict that OI(63 micrometers) and IR rotational lines of CO and H2O dominate the cooling in the freefalling region 10-1000 AU from the protostar. The freefalling gas supersonically hits the protoplanetary disk orbiting the protostar, forming an accretion shock with strong IR emission in rotational lines of H2O and OH, and OI(63 microns). The accretion shock spectra and line profiles depend on the mass flux through the shock and the typical distance r-bar at which the freefalling gas strikes the disk. The line widths are of order the Keplerian speed, or approx. 10(r-bar/10AU)(exp -0.5) km/s, for the accretion shock lines, and less for the lines from the infalling gas. Measurements of the IR line fluxes and profiles from the freefalling gas and the accretion shock diagnoses how a protostar and disk are formed and requires high sensitivity and high spectral and spatial resolving power. SOFIA will be the optimum observatory for many of these lines, although ISO will contribute and the KAO may make a few pioneering detections.
Fast Time Resolved Spectral Analysis of VLF Banded Emissions
F. V. Coroniti; R. W. Fredricks; C. F. Kennel; F. L. Scarf
Several classes of VLF banded emissions acquired by the short antenna Ogo 5 electric field detector are investigated by using high time resolution spectral techniques. The fastest temporal resolution of statistically independent spectra is 50 msec; individual spectra are taken every 12.5 msec. VLF banded rising chorus spectra possessed single and\\/or multiple frequency modulated bursts; discrete single modes with unchanging
The PG X-Ray QSO Sample: Links among X-ray, UV & Optical Spectra
Beverley J. Wills; M. S. Brotherton; A. Laor; D. Wills; B. J. Wilkes; G. J. Ferland
A unique, essentially complete sample of 22 QSOs, with high quality soft X-ray spectra from ROSAT, as well as HST and optical spectrophotometry from below Ly-alpha to above H-alpha, is being used to investigate the relationships among the ionizing continuum and the optical and UV continuum, emission and absorption lines. Here we present a first analysis showing that optical `Eigenvector 1' linking steeper soft X-ray spectra with increasing optical Fe II strength, decreasing [O III] 5007 emission, and narrower BLR H-beta emission, extends to the UV emission lines, and is manifested by weaker C IV 1549 emission, stronger Si III] 1892/C III] 1909 ratio, and narrower C III] 1909 emission. Steeper soft X-ray spectra have been linked to higher L/L_Edd ratios, thus apparently linking BLR densities, high and low ionization gas, and kinematics, to the accretion process.
Determining the modal mineralogy of mafic and ultramafic igneous rocks using thermal emission spectroscopy
Victoria E. Hamilton; Philip R. Christensen
The modal mineralogies of 20 mafic and ultramafic igneous rocks were determined from their thermal infrared emission spectra using a linear deconvolution approach, which uses a library of end-member mineral spectra to model a bulk rock spectrum. Over 90% of the modes obtained from thermal emission spectra agree with modes obtained by traditional optical analyses to within the stated error
Theoretical Studies of Molecular Spectra
NASA Technical Reports Server (NTRS)
McKay, Christopher (Technical Monitor); Freedman, Richard S.
This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.
Varying Faces of Photospheric Emission in Gamma-Ray Bursts
Axelsson, M
Among the more than 1000 gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope, a large fraction show narrow and hard spectra inconsistent with non-thermal emission, signifying optically thick emission from the photosphere. However, only a few of these bursts have spectra consistent with a pure Planck function. We will discuss the observational features of photospheric emission in these GRBs as well as in the ones showing multi-component spectra. We interpret the observations in light of models of subphotospheric dissipation, geometrical broadening and multi-zone emission, and show what we can learn about the dissipation mechanism and properties of GRB jets.
NASA Technical Reports Server (NTRS)
Petrash, D. A.; Diehl, L. A.; Jones, R. E.; Mularz, E. J.
Control of the gaseous pollutant emissions of aircraft engines is considered in terms of the emission standards for six classes of aircraft engines. Emphasis is placed on combustor design concepts to significantly reduce emissions levels and lean-burning techniques to lower flame temperature, to reduce the oxides of nitrogen in the gaseous emissions.
NASA Astrophysics Data System (ADS)
Lyashko, D. A.; Tsymbal, V. V.; Makaganiuk, V. A.
The current software was developed at the Taurida National University, astronomy department of physics faculty by Lyashko D.A., Tsymbal V.V. This programm comlex can be adapted according namely to individual spectrograph. All spectra processing goes automatically, so in this way it becomes possible to minimize user interaction with programm. It is very convinient and does not require special training for using it. In this case we can exclude human element and so then, output data corruption. The algotithm of processing due to differences between spectrographs is described in this paper.
NASA Technical Reports Server (NTRS)
Wilkes, Belinda J.
The results of the initial stage of the CfA survey of quasar energy distributions are reviewed. Einstein imaging proportional counter spectra of 33 quasars have been studied by fitting a single power law slope and absorption by an equivalent column density of neutral hydrogen. Comparison with the higher energy HEAO-A2 data leads to a two-component model for the X-ray spectrum. The X-ray column density is systematically lower than the 21-cm measured Galactic column density along the same line of sight.
Interpretation of electron spectra in morningside pulsating aurorae
D. S. Evans; G. T. Davidson; H. D. Voss; W. L. Imhof; J. Mobilia; Y. T. Chiu
Energy spectra of precipitating electrons in morningside aurorae were obtained with instruments on the NOAA 6 satellite during several passes through the southern auroral zone in 1982. It is substantiated with the aid of coordinated data from particle detectors and a photometer in the Simulated Emission of Energetic Particles experiment payload on satellite S81-1 that the precipitation obserbed by NOAA
Investigating the Near-Infrared Properties of Planetary Nebulae II. Medium Resolution Spectra. 2; Medium Resolution Spectra
NASA Technical Reports Server (NTRS)
Hora, Joseph L.; Latter, William B.; Deutsch, Lynne K.
We present medium-resolution (R approximately 700) near-infrared (lambda = 1 - 2.5 micrometers) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H1 emission line-dominated PNe, H1 and H2 emission line PNe, H2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects falling into the first group and the C-rich objects in the groups. Other spectral features were observed in all catagories, such as continuum emission from the central star, and warm dust continuum emission towards the long wavelength end of the spectra. H2 was detected in four PNe in this survey for the first time. An analysis was performed using the H2 line ratios in all of the PN spectra in the survey where a sufficient number of lines were observed to determine the ortho-to-para ratio and the rotational and vibrational excitation temperatures of the H-2 in those objects. One unexpected result from this analysis is that the H-2 is excited by absorption of ultraviolet photons in most of the PNe, although there are several PNe in which collisional excitation plays an important role. The correlation between bipolar morphology and H2 emission has been strengthened with the new detections of H2 in this survey.
Total luminescence spectroscopy was applied to the fluorescence characterization of humic substances obtained from the International Humic Substances Society (IHSS). Results show that total luminescence spectra, represented as excitation-emission matrices (EEMs), may be used to d...
Glows in the Dark�Emission Lines and Nebulae
Keith Robinson
So far we�ve been dealing mainly with the continuum and absorption lines in the spectra of normal stars. It�s time we looked\\u000a at emission lines; some stars like Wolf- Rayet stars and symbiotic stars together with Mira variables do produce emission\\u000a lines in their spectra. However, the best place to introduce our emission line studies is gaseous nebulae and planetary
Decomposition of protein tryptophan fluorescence spectra into log-normal components. I. Decomposition algorithms.
Burstein, E A; Abornev, S M; Reshetnyak, Y K
Two algorithms of decomposition of composite protein tryptophan fluorescence spectra were developed based on the possibility that the shape of elementary spectral component could be accurately described by a uniparametric log-normal function. The need for several mathematically different algorithms is dictated by the fact that decomposition of spectra into widely overlapping smooth components is a typical incorrect problem. Only the coincidence of components obtained with various algorithms can guarantee correctness and reliability of results. In this paper we propose the following algorithms of decomposition: (1) the SImple fitting procedure using the root-Mean-Square criterion (SIMS) operating with either individual emission spectra or sets of spectra measured with various quencher concentrations; and (2) the pseudo-graphic analytical procedure using a PHase plane in coordinates of normalized emission intensities at various wavelengths (wavenumbers) and REsolving sets of spectra measured with various Quencher concentrations (PHREQ). The actual experimental noise precludes decomposition of protein spectra into more than three components. PMID:11509382
Modelling Spectra and Lightcurves from Supernovae
NASA Astrophysics Data System (ADS)
Frey, Lucille; Even, W.; Whalen, D.; Fryer, C.; Hungerford, A.; Fontes, C.
Explosive transient astronomy is entering an era where supernovae (SNe) and gamma-ray bursts will be observed in real time with surveys like the LSST and Pan-STARRS, probing the universe back to very early times. The discovery of Pop III SNe could reveal many details about the formation and evolution of the first stars. Observations of shock breakout in SNe will provide new information about the engines powering these explosions. Shock breakout occurs when the shock wave from core collapse reaches an optically thin region and radiation can stream out. This first burst of radiation interacts with the star's immediate surroundings, showing the effects of the surrounding environment on emission and evolution. This profusion of data will contain brief snapshots from a wide range of progenitor systems which simulations can help interpret and explain. We present a new pipeline for creating model supernova spectra and lightcurves using radiation-hydrodynamic simulations and a new Spectrum code. Spectrum maps 1-D or 2-D data onto a two dimensional grid and assumes rotational symmetry, using monochromatic opacities to calculate emission and absorption as a function of radius and angle. We use these spectra to create lightcurves in any band from infrared to x-ray. This pipeline is being used to study the effects of stellar environment on core-collapse and Type Ia SNe, as well as several types of Pop III SNe.
NASA Astrophysics Data System (ADS)
Tomkov�, E.
Methods of TDS spectra analysis start usually from the Polanyi-Wigner desorption rate equation. The Redhead approximative solution of the equation can be rearranged into a reduced form in which it serves as an analytical expression for the desorption rate versus time or temperature. Fitting the analytical form to an experimental curve we can confirm or deny the invariability of kinetic parameters � a desorption energy Ed and a preexponential factor ?l � and determine their values. If the parameters depend on surface coverage ? the application of the reduced form allows us to determine their values at ??0 and ?? ?0 and estimate the dependence Ed( ?), ?(?) from a single TDS spectrum. The method proposed in this paper is valid for the first-order kinetics of desorption; for the estimation mentioned above an assumption is made that desorption sites are identical and that E d as well as ?l changes with ? monotonously.
The Excitation Spectra of Two-Photon Induced Fluorescence in Xanthene Dyes
Takanori Wakebe; Edward Van Keuren
Two-photon excitation spectra of xanthene dyes in ethanol weremeasured by observing fluorescence emission after excitation by lightwith wavelengths from 780 to 1260 nm. The normalized spectra showedlarge two-photon induced fluorescence at higher energies and twomoderate peaks near the one-photon absorption band. These featuresagreed well with the two-photon excitation spectra reported by otherauthors. The peaks near the one-photon absorption band may
Vibrational spectra of 9-xanthone
NASA Astrophysics Data System (ADS)
Zwarich, R.; Binbrek, O. S.
Polarized i.r. spectra of partially oriented 9-xanthone crystals grown from the melt between pressed salt plates and the i.r. spectra in a variety of solvents have been recorded from 180 to 3500 cm -1. The depolarization ratios of the Raman lines in the melt have been measured and the polarized Raman spectra of a crystal in all possible orientations have been recorded. The experimental assignment is compared with a set of calculated values.
Polarization effects in cutaneous autofluorescent spectra
NASA Astrophysics Data System (ADS)
Borisova, E.; Angelova, L.; Jeliazkova, Al.; Genova, Ts.; Pavlova, E.; Troyanova, P.; Avramov, L.
Used polarized light for fluorescence excitation one could obtain response related to the anisotropy features of extracellular matrix. The fluorophore anisotropy is attenuated during lesions' growth and level of such decrease could be correlated with the stage of tumor development. Our preliminary investigations are based on in vivo point-by-point measurements of excitation-emission matrices (EEM) from healthy volunteers skin on different ages and from different anatomical places using linear polarizer and analyzer for excitation and emission light detected. Measurements were made using spectrofluorimeter FluoroLog 3 (HORIBA Jobin Yvon, France) with fiber-optic probe in steady-state regime using excitation in the region of 280-440 nm. Three different situations were evaluated and corresponding excitation-emission matrices were developed - with parallel and perpendicular positions for linear polarizer and analyzer, and without polarization of excitation and fluorescence light detected from a forearm skin surface. The fluorescence spectra obtained reveal differences in spectral intensity, related to general attenuation, due to filtering effects of used polarizer/analyzer couple. Significant spectral shape changes were observed for the complex autofluorescence signal detected, which correlated with collagen and protein cross-links fluorescence, that could be addressed to the tissue extracellular matrix and general condition of the skin investigated, due to morphological destruction during lesions' growth. A correlation between volunteers' age and the fluorescence spectra detected was observed during our measurements. Our next step is to increase developed initial database and to evaluate all sources of intrinsic fluorescent polarization effects and found if they are significantly altered from normal skin to cancerous state of the tissue, this way to develop a non-invasive diagnostic tool for dermatological practice.
The Ultraviolet Emission Spectra of AN HII Region
NASA Astrophysics Data System (ADS)
Cox, Nancy
Ultraviolet emission spectra of sunbeds. - PubMed - NCBI
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chlorophyll fluorescence in thisorganism. In Por- phyridium (red alga) and Anacystis (blue-green alga, in green as well as in red and blue-green algae, is discussed. INTRODUCTION Comparison of absorption with frequency. In Chlorella (green alga) a sharp drop of '(iv) is indicated towards the lower frequencies
Effect of insulator sleeve material on the x-ray emission from a plasma focus device
Hussain, S.; Badar, M. A. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Shafiq, M.; Zakaullah, M. [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)
The effect of insulator sleeve material on x-ray emission from a 2.3 kJ Mather type plasma focus device operated in argon-hydrogen mixture is investigated. The time and space resolved x-ray emission characteristics are studied by using a three channel p-i-n diode x-ray spectrometer and a multipinhole camera. The x-ray emission depends on the volumetric ratio of argon-hydrogen mixture as well as the filling pressure and the highest x-ray emission is observed for a volumetric ratio 40% Ar to 60%H{sub 2} at 2.5 mbar filling pressure. The fused silica insulator sleeve produces the highest x-ray emission whereas nonceramic insulator sleeves such as nylon, Perspex, or Teflon does not produce focus or x-rays. The pinhole images of the x-ray emitting zones reveal that the contribution of the Cu K{alpha} line is weak and plasma x-rays are intense. The highest plasma electron temperature is estimated to be 3.3 and 3.6 keV for Pyrex glass and fused silica insulator sleeves, respectively. It is speculated that the higher surface resistivity of fused silica is responsible for enhanced x-ray emission and plasma electron temperature.
Temporal and spectral dependence of samariuom x-ray emission in subpicosecond and nanosecond laser-produced plasmas
NASA Astrophysics Data System (ADS)
Chenais-Popovics, Claude J.; Audebert, Patrick; Fajardo, M.; Shepherd, Ronnie L.; Peyrusse, Olivier; Gauthier, Jean-Claude J.
Ultra-short x-ray sources are generated by focusing sub- picosecond lasers on massive targets. The emission duration of a samarium x-ray source produced with a 100 TW sub- picosecond laser was measured using an ultra-fast X-ray streak camera. The spectral range was limited around 7.5-8.5 angstrom, the range in which samarium can be used as a backlighter for K(alpha) aluminum absorption experiments. The spectral time-evolution and the duration of samarium emission were measured. Preliminary calculations performed with non-local-thermodynamic equilibrium atomic physics show the plasma cooling which occurs with a characteristic time longer than predicted by radiative hydrocode simulations.
Single Photon Infrared Emission Spectroscopy: A Study of IR Emission from UV Laser Excited PAHs between 3 and 15 m
Cohen, Ronald C.
Single Photon Infrared Emission Spectroscopy: A Study of IR Emission from UV Laser Excited PAHs (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs PAHs. Lorentzian band shapes were convoluted with the monochromator- slit function in order
Interpreting Chromosome Aberration Spectra
NASA Technical Reports Server (NTRS)
Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer
Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.
Thermal Emission Spectroscopy of 1 Ceres: Evidence for Olivine
NASA Technical Reports Server (NTRS)
Witteborn, Fred. C.; Roush, Ted L.; Cohen, Martin
Thermal emission spectra of the largest asteroid, 1 Ceres, obtained from the Kuiper Airborne Observatory display features that may provide information about its surface mineralogy. The emissivity, obtained by dividing the spectra by a standard thermal model, is compared with emissivity spectra of olivines and phyllosilicates deduced via Kirchoff's law from reflectivity measurements. The spectra provide a fairly good match to fine grained olivines (0 to 5 micrometer size range). The smoothness of the spectrum beyond 18 micrometers is an indication of particles smaller than 50 micrometers. While the abrupt rise in emissivity near 8 micrometers matches many silicates, the distinct emissivity minimum centered near 12.8 micrometers is consistant with iron-poor olivines, but not with phyllosilicates. It suggests the presence of opaques and does not exclude a mixture with organics and fine-grained phyllosilicates.
COMPOSITE SPECTRA IN MERGING U/LIRGs CAUSED BY SHOCKS
Rich, J. A. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Kewley, L. J.; Dopita, M. A., E-mail: email@example.com [Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd., Weston ACT 2611 (Australia)
We present a key result from our optical integral field spectroscopic survey of 27 nearby ultraluminous and luminous infrared galaxies (U/LIRGs) from the Great Observatory All-Sky LIRG Survey. Using spatially resolved multi-component emission line fitting to trace the emission line ratios and velocity dispersion of the ionized gas, we quantify for the first time the widespread shock ionization in gas-rich merging U/LIRGs. Our results show a fractional contribution to the total observed H?�flux from radiative shocks increasing from a few percent during early merger stages to upward of 60% of the observed optical emission line flux in late-stage mergers. We compare our resolved spectroscopy to nuclear spectra and find that 3/4 of the galaxies in our sample that would be classified as ''composite'' based on optical spectroscopy are primarily characterized by a combination of star formation and merger-driven shocks. Our results have important implications for the interpretation of ''composite'' rest-frame optical spectra of U/LIRGs as starburst+active galactic nucleus (AGN), as the shock emission combined with star formation can mimic ''composite'' optical spectra in the absence of any contribution from an AGN.
Photoluminescence spectra of some ternary and quaternary chalcopyrite semiconductors
Abou-Elfotouh, F.; Dunlavy, D.J.; Kazmerski, L.L.; Albin, D.; Bachman, K.J.; Menner, R.
Photoluminescence (PL) emission spectra of single crystals and thin films of CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ compounds have been investigated at various measuring temperatures, and compared with the emission from CuGaSe/sub 2/ and CuInSe/sub 2/. The observed PL spectra consisted of two groups of emission lines: the near-band-gap group (A) and the lower energy group (B). It was found that the type of emission obtained is determined by the amount of stoichiometry and molecularity deviations. The PL data also showed a correspondence between the defect related transitions from the CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ solid solution and CuGaSe/sub 2/ for x<0.5. Based on the intrinsic defect states in the two components CuInSe/sub 2/ and CuGaSe/sub 2/, the predominant defect states transitions in the solid solution are defined for the m<1 and ..delta..S>0. Interpretation of the PL spectra of Se-deficient compounds with m>1 are rather complicated, and much work remains to be done before the defect chemistry of CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ could be fully understood.
Features in the spectra of gamma-ray bursts
NASA Technical Reports Server (NTRS)
Stanek, Krzysztof Z.; Paczynski, Bohdan; Goodman, Jeremy
Gravitational lensing of cosmological gamma-ray bursts by objects in the mass range about 10 exp 17 to 10 exp 20 g (femtolensing) may introduce complicated interference patterns that might be interpreted as absorption or emission lines in the bursts' spectra. This phenomenon, if detected, may be used as a unique probe of dark matter in the universe. The BATSE spectral data should allow one to detect such spectral features or to put significant upper limits on the cosmic density of a dark matter component that may be in the femtolensing range. Software to generate theoretical spectra has been developed, and it is accessible over the computer network with anonymous ftp.
Measurement of charged particle transverse momentum spectra in deep inelastic scattering
C. Adloff; S. Aid; M. Anderson; V. Andreev; B. Andrieu; A. Babaev; J. B�hr; J. B�n; Y. Ban; P. Baranov; E. Barrelet; R. Barschke; W. Bartel; M. Barth; U. Bassler; H. P. Beck; M. Beck; H.-J. Behrend; A. Belousov; Ch. Berger; G. Bernardi; G. Bertrand-Coremans; M. Besan�on; R. Beyer; P. Biddulph; P. Bispham; J. C. Bizot; V. Blobel; K. Borras; F. Botterweck; V. Boudry; A. Braemer; W. Braunschweig; V. Brisson; W. Br�ckner; P. Bruel; D. Bruncko; C. Brune; R. Buchholz; L. B�ngener; J. B�rger; F. W. B�sser; A. Buniatian; S. Burke; M. J. Burton; D. Calvet; A. T. Campbell; T. Carli; M. Charlet; D. Clarke; A. B. Clegg; B. Clerbaux; S. Cocks; J. G. Contreras; C. Cormack; J. A. Coughlan; A. Courau; M.-C. Cousinou; G. Cozzika; L. Criegee; D. G. Cussans; J. Cvach; S. Dagoret; J. B. Dainton; W. D. Dau; K. Daum; M. David; C. L. Davis; B. Delcourt; A. De Roeck; E. A. De Wolf; M. Dirkmann; P. Dixon; P. Di Nezza; W. Dlugosz; C. Dollfus; K. T. Donovan; J. D. Dowell; H. B. Dreis; A. Droutskoi; O. D�nger; H. Duhm; J. Ebert; T. R. Ebert; G. Eckerlin; V. Efremenko; S. Egli; R. Eichler; F. Eisele; E. Eisenhandler; E. Elsen; M. Erdmann; W. Erdmann; A. B. Fahr; L. Favart; A. Fedotov; R. Felst; J. Feltesse; J. Ferencei; F. Ferrarotto; K. Flamm; M. Fleischer; M. Flieser; G. Fl�gge; A. Fomenko; J. Form�nek; J. M. Foster; G. Franke; E. Fretwurst; E. Gabathuler; K. Gabathuler; F. Gaede; J. Garvey; J. Gayler; M. Gebauer; H. Genzel; R. Gerhards; A. Glazov; L. Goerlich; N. Gogitidze; M. Goldberg; D. Goldner; K. Golec-Biernat; B. Gonzalez-Pineiro; I. Gorelov; C. Grab; H. Gr�ssler; T. Greenshaw; R. K. Griffiths; G. Grindhammer; A. Gruber; C. Gruber; T. Hadig; D. Haidt; L. Hajduk; T. Haller; M. Hampel; W. J. Haynes; B. Heinemann; G. Heinzelmann; R. C. W. Henderson; H. Henschel; I. Herynek; M. F. Hess; K. Hewitt; W. Hildesheim; K. H. Hiller; C. D. Hilton; J. Hladk�; M. H�ppner; D. Hoffmann; T. Holtom; R. Horisberger; V. L. Hudgson; M. H�tte; M. Ibbotson; H. Itterbeck; A. Jacholkowska; C. Jacobsson; M. Jaffre; J. Janoth; D. M. Jansen; T. Jansen; L. J�nsson; D. P. Johnson; H. Jung; P. I. P. Kalmus; M. Kander; D. Kant; R. Kaschowitz; U. Kathage; J. Katzy; H. H. Kaufmann; O. Kaufmann; M. Kausch; S. Kazarian; I. R. Kenyon; S. Kermiche; C. Keuker; C. Kiesling; M. Klein; C. Kleinwort; G. Knies; T. K�hler; J. H. K�hne; H. Kolanoski; S. D. Kolya; V. Korbel; P. Kostka; S. K. Kotelnikov; T. Kr�merk�mper; M. W. Krasny; H. Krehbiel; D. Kr�cker; H. K�ster; M. Kuhlen; T. Kurca; J. Kurzh�fer; D. Lacour; B. Laforge; M. P. J. Landon; W. Lange; U. Langenegger; A. Lebedev; F. Lehner; S. Levonian; G. Lindstr�m; M. Lindstroem; F. Linsel; J. Lipinski; B. List; G. Lobo; P. Loch; J. W. Lomas; G. C. Lopez; V. Lubimov; D. Liike; L. Lytkin; N. Magnussen; E. Malinovski; R. Maracek; P. Marage; J. Marks; R. Marshall; J. Martens; G. Martin; R. Martin; H.-U. Martyn; J. Martyniak; T. Mavroidis; S. J. Maxfield; S. J. McMahon; A. Mehta; K. Meier; F. Metlica; A. Meyer; H. Meyer; J. Meyer; P.-O. Meyer; A. Migliori; S. Mikocki; D. Milstead; J. Moeck; F. Moreau; J. V. Morris; E. Mroczko; D. M�ller; G. M�ller; K. M�ller; P. Mur�n; V. Nagovizin; R. Nahnhauer; B. Naroska; Th. Naumann; I. N�gri; P. R. Newman; D. Newton; H. K. Nguyen; T. C. Nicholls; F. Niebergall; C. Niebuhr; Ch. Niedzballa; H. Niggli; G. Nowak; G. W. Noyes; T. Nunnemann; M. Nyberg-Werther; M. Oakden; H. Oberlack; J. E. Olsson; D. Ozerov; P. Palmen; E. Panaro; A. Panitch; C. Pascaud; G. D. Patel; H. Pawletta; E. Peppel; E. Perez; J. P. Phillips; A. Pieuchot; D. Pitzl; G. Pope; B. Povh; S. Prell; K. Rabbertz; G. R�del; P. Reimer; S. Reinshagen; H. Rick; F. Riepenhausen; S. Riess; E. Rizvi; P. Robmann; P. H. E. Roloff; R. Roosen; K. Rosenbauer; A. Rostovtsev; F. Rouse; C. Royon; K. R�ter; S. Rusakov; K. Rybicki; D. P. C. Sankey; P. Schacht; S. Schiek; S. Schleif; P. Schleper; W. von Schlippe; D. Schmidt; G. Schmidt; L. Schoeffel; A. Sch�ning; V. Schr�der; E. Schuhmann; B. Schwab; F. Sefkow; R. Sell; A. Semenovy; V. Shekelyan; I. Sheviakov; L. N. Shtarkov; G. Siegmon; U. Siewert; Y. Sirois; I. O. Skillicorni; F Smirnov; V. Solochenko; Y. Soloviev; A. Specka; J. Spiekermann; S. Spielman; H. Spitzer; F. Squinabol; F Steffen; F. Steinberg; H. Steiner; J. Steinhart; B. Stella; A. Stellberger; P. J. Stier; J. Stiewe; U. St��lein; K. Stolze; U. Straumann; W. Struczinski; J. P. Sutton; S. Tapprogge; V. Tchernyshov; S. Tchetchelnitski; J. Theissen; C. Thiebaux; G. Thompson; N. Tobien; R. Todenhagen; P. Tru�l; G. Tsipolitis; J. Turnau; J. Tutas; E. Tzamariudaki; P. Uelkes; A. Usik; S. Valk�r; A. Valk�rov�; C. Vall�e; D. Vandenplas; P. Van Esch; P. Van Mechelen; Y. Vazdik; P. Verrecchia; G. Villet; K. Wacker; A. Wagener; M. Wagener; B. Waugh; G. Weber; M. Weber; D. Wegener; A. Wegner; T. Wengler; M. Werner; L. R. West; T. Wilksen; S. Willard; M. Winde; G.-G. Winter
Transverse momentum spectra of charged particles produced in deep inelastic scattering are measured as a function of the kinematic variablesx and Q2 using the H1 detector at the epcollider HERA. The data are compared to different parton emission models, either with or without ordering of the emissions in transverse momentum. The data provide evidence for a relatively large amount of
Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium:. [The Chandra Grating Spectra of XTE J1817-330
NASA Technical Reports Server (NTRS)
Gatuzz, E.; Garcia, J.; Mendoza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.
We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 Angstrom broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 Angstroms) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N(sub H) = 1.38 +/- 0.01 � 10(exp 21) cm(exp -2); an ionization parameter of log xi = -2.70 +/- 0.023; an oxygen abundance of A(sub O) = 0.689 (+0.015/-0.010); and ionization fractions of O(sub I)/O = 0.911, O(sub II)/O = 0.077, and O(sub III)/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields A(sub O) = 0.952(+0.020/-0.013), a value close to solar that reinforces the new standard.We identify several atomic absorption lines-K(alpha), K(beta), and K(gamma) in O(sub I) and O(sub II) and K(alpha) in O(sub III), O(sub VI), and O(sub VII)-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated with ISM cold absorption.
Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium: The Chandra Grating Spectra of XTE J1817-330
NASA Technical Reports Server (NTRS)
Gatuzz, E.; Garcia, J.; Menodza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.
We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra towards the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pileup effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain: a column density of N(sub H) = 1.38 +/- 0.01 x 10(exp 21) cm(exp -2); ionization parameter of log xi = .2.70 +/- 0.023; oxygen abundance of A(sub O) = 0.689(exp +0.015./-0.010); and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval (1998), a rescaling with the revision by Asplund et al. (2009) yields A(sub O) = 0.952(exp +0.020/-0.013, a value close to solar that reinforces the new standard. We identify several atomic absorption lines.K-alpha , K-beta, and K-gamma in O I and O II; and K-alpha in O III, O VI, and O VII--last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated to ISM cold absorption.
[The monomer electronic spectra and fluorescence spectra of some metal phthalocyanines].
Huang, J; Liu, E; Yang, S; Chen, N; Huang, J; Duan, J; Chen, Y
The monomer electronic absorption spectra of the ZnPcS2P2 (disulfonated diphthalimidomethyl phthalocyanine zinc) in 11 kinds of solvents and 5 kinds of unsubstituted metal phthalocyanines in DMF were investigated. The monomer electronic absorption spectra of some substituted phthalocyanine zinc including ZnPcS4 (tetrasulfonated phthalocyanine zinc), ZnPcS4 (tetraphthalimidomethyl phthalocyanine zinc), ZnPc(NO2)4 (tetranitro phthalocyanine zinc) and ZnPcS2P2 in the same solvent were also studied. The result showed that (1) with the strengthening of coordination ability of the solvent, the maximum absorption wavelength of ZnPcS2P2 increased slightly. (2) with the increasing of electronegativity of central ion, the maximum absorption wavelength of MPcs had a little blue shift. (3) the electron-donating substituting group caused slightly blue shift. The monomer fluorescence spectra of ZnPcS4, ZnPcP4, and ZnPcS2P2 in different solvents were determined. The result showed that (1) the electron-withdrawing substituting group caused slightly red shift of the fluorescence spectra. (2) with the strenghtening of coordination ability of the solvent, the maximum emission wavelength increased slightly. (3) the fluorescence intensity of ZnPcS2P2 in the solution which contains Cremophor EL was remarkable stronger than that in other solvents. This is an important suggest to the development of photodynamic diagnose agent. The effect of solvents, central ions and substituents on spectra were partly explained by means of the quantrum chemistry. PMID:12953463
Spatially Resolved Spectra of the Red Rectangle in the N-band
NASA Astrophysics Data System (ADS)
Miyata, Takashi; Kataza, H.; Okamoto, Y.; Sako, S.; Takubo, S.; Onaka, T.; Yamashita, T.
We have observed the Red Rectangle by our newly developed instrument COMICS attached on the SUBARU 8.2 m telescope, and obtained images and spectra in the N-band (8-13.2 microns). Diffraction limited spatial resolution (~0.35 arcsec) was almost achieved, revealing differences of dust emission profiles with its distance from the central star. In the nebula region (distance > 260 AU), UIR emissions at 7.7, 8.6, 11.27, and 12.7 microns were prominent, while spectra around the central star (distance < 260 AU) are dominated by strong continuum emissions.
Cluster analysis on mass spectra of biogenic secondary organic aerosol
NASA Astrophysics Data System (ADS)
Spindler, C.; Kiendler-Scharr, A.; Kleist, E.; Mensah, A.; Mentel, T.; Tillmann, R.; Wildt, J.
Biogenic secondary organic aerosols (BSOA) are of high importance in the atmosphere. The formation of SOA from the volatile organic compound (VOC) emissions of selected trees was investigated in the JPAC (J�lich Plant Aerosol Chamber) facility. The VOC (mainly monoterpenes) were transferred into a reaction chamber where vapors were photo-chemically oxidized and formed BSOA. The aerosol was characterized by aerosol mass spectrometry (Aerodyne Quadrupol-AMS). Inside the AMS, flash-vaporization of the aerosol particles and electron impact ionization of the evaporated molecules cause a high fragmentation of the organic compounds. Here, we present a classification of the aerosol mass spectra via cluster analysis. Average mass spectra are produced by combination of related single mass spectra to so-called clusters. The mass spectra were similar due to the similarity of the precursor substances. However, we can show that there are differences in the BSOA mass spectra of different tree species. Furthermore we can distinguish the influence of the precursor chemistry and chemical aging. BSOA formed from plants exposed to stress can be distinguished from BSOA formed under non stressed conditions. Significance and limitations of the clustering method for very similar mass spectra will be demonstrated and discussed.
The 8-13 micron spectra of comets and the composition of silicate grains
NASA Astrophysics Data System (ADS)
Hanner, M. S.; Lynch, D. K.; Russell, R. W.
We have analyzed the existing spectra of seven comets which show an emission feature at 7.8-13 micrometers. Most have been converted to a common calibration, taking into account the SiO feature in late-type standard stars. The spectra are compared with spectra of the Trapezium, interplanetary dust particles (IDPs), laboratory mineral samples, and small particle emission models. The emission spectra show a variety of shapes; there is no unique 'cometary silicate'. A peak at 11.20-11.25 micrometers, indicative of small crystalline olivine particles, is seen in only three comets of this sample, P/Halley, Bradfield 1987 XXIX, and Levy 1990 XX. The widths of the emission features range from 2.6 to 4.1 micrometers (FWHM). To explain the differing widths and the broad 9.8 micrometers maximum, glassy silicate particles, including both pyroxene and olivine compositions, are the most plausible candidates. Calculations of emission models confirm that small grains of glassy silicate well mixed with carbonaceous material are plausible cometary constituents. No single class of chondritic aggregate IDPs exhibits spectra closely matching the comet spectra. A mixture of IDP spectra, particularly the glass-rich aggregates, approximately matches the spectra of comets P/Halley, Levy, and Bradfield 1987 XXIX. Yet, if comets are simply a mix of IDP types, it is puzzling that the classes of IDPs are so distinct. None of the comet spectra match the spectrum of the Trapezium. Thus, the mineralogy of the cometary silicates is not the same as that of the interstellar medium. The presence of a component of crystalline silicates in comets may be evidence of mixing between high- and low-temperature regions in the solar nebula.
Channeling effect in electronic spectra produced by grazing impact of fast protons on insulator surfaces
C. D. Archubi; M. S. Gravielle
Electron emission due to grazing scattering of fast protons from LiF and KCl surfaces is studied under axial channeling conditions. The differential electron emission probability is calculated within a distorted-wave formalism, taking into account realistic channeled trajectories. For electronic spectra along low-index crystallographic directions, we find that channeling effects on the electron emission yield depend strongly on the penetration rate
IntrAst2 (Petrovay) Spectra STELLAR SPECTRA
Petrovay, Krist�f
) Spectra Kirchhoff's laws of spectroscopy (1860): 1. The spectrum of a hot body (solid body or opaque and spectrum of hydrogen (H I): Lyman series: ultraviolet domain Balmer series: optical domain Paschen series
A Suzaku Observation of the Low-Ionization Fe-Line Emission from RCW 86
Masaru Ueno; Rie Sato; Jun Kataoka; Aya Bamba; Ilana Harrus; Junko Hiraga; John P. Hughes; Caroline A. Kilbourne; Katsuji Koyama; Motohide Kokubun; Hiroshi Nakajima; Masanobu Ozaki; Robert Petre; Tadayuki Takahashi; Takaaki Tanaka; Hiroshi Tomida; Hiroya Yamaguchi
The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant (SNR) RCW 86 in February 2006 to study the nature of the 6.4 keV emission line first detected with the Advanced Satellite for Cosmology and Astronomy (ASCA). The new data confirm the existence of the line, localizing it for the first time; most of the line emission is adjacent and interior to the forward shock and not at the locus of the continuum hard emission. We also report the first detection of a 7.1 keV line that we interpret as the K-beta emission from low-ionization iron. The Fe-K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with n_{e}t <~ 10^9 cm^-3 s and kT_{e} ~ 5 keV. This combination of low n_{e}t and high kT_{e} suggests collisionless electron heating in an SNR shock. The Fe K-alpha line shows evidence for intrinsic broadening, with a width of 47 (34--59) eV (99% error region). The difference of the spatial distributions of the hard continuum above 3 keV and the Fe-K line emission support a synchrotron origin for the hard continuum.
Longslit Spectra of the Galaxy NGC 1569
NASA Technical Reports Server (NTRS)
Duenas, Ely
Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.
Longslit Spectra of the Galaxy NGC 1569
NASA Astrophysics Data System (ADS)
Duenas, Ely
Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.
Radioactive sample effects on EDXRF spectra
Worley, Christopher G [Los Alamos National Laboratory
Energy dispersive X-ray fluorescence (EDXRF) is a rapid, straightforward method to determine sample elemental composition. A spectrum can be collected in a few minutes or less, and elemental content can be determined easily if there is adequate energy resolution. Radioactive alpha emitters, however, emit X-rays during the alpha decay process that complicate spectral interpretation. This is particularly noticeable when using a portable instrument where the detector is located in close proximity to the instrument analysis window held against the sample. A portable EDXRF instrument was used to collect spectra from specimens containing plutonium-239 (a moderate alpha emitter) and americium-241 (a heavy alpha emitter). These specimens were then analyzed with a wavelength dispersive XRF (WDXRF) instrument to demonstrate the differences to which sample radiation-induced X-ray emission affects the detectors on these two types of XRF instruments.
NASA Astrophysics Data System (ADS)
Patil, R. R.; Moharil, S. V.
Cu + is known to exhibit characteristic luminescence corresponding to 3 d94 s ? 3 d10 transition. Data for excitation and emission of Cu + in alkali halides have been published. Earlier works report failure to dope Cu + in lithium fluoride. However, we discovered photoluminescence in LiF: Mg, Cu, P, a commercial TL phosphor. A peculiar synthesis led to similar emission in LiF: Cu. The emission and excitation spectra for LiF: Cu and the comparison with LiF: Mg, Cu, P, are presented. It is claimed in this communication that the emission is due to Cu +.
The mid-infrared spectra of normal galaxies
NASA Technical Reports Server (NTRS)
Helou, G.; Lu, N.; Werner, M.; Malhotra, S.; Silbermann, N.
The mid-infrared spectra (2.5-5 and 5.7-11.6 mu m) obtained by ISOPHOT reveal the interstellar medium emission from galaxies powered by star formation to be strongly dominated by the aromatic features at 6.2, 7.7, 8.6, and 11.3 mu m. Additional emission appears in between the features, and an underlying continuum is clearly evident at 3-5 mu m. This continuum would contribute about a third of the luminosity in the 3-13 mu m range. The features together carry 5%-30% of the 40-120 mu m. range.FIR) luminosity.
Abundance Calculations Using Synthetic Spectra
NASA Astrophysics Data System (ADS)
Pintado, O.; Adelman, S.
Elemental abundance analysis are derived for the Mercury-Manganese star HR4817 (B8II/III), using CCD recorded exposures obtained with the EBASIM echelle spectrograph in the CASLEO (Complejo Astron�mico El Leoncito) 2.1 m telescope in Argentina. The spectra coverage is 390-900 nm. The abundances and microturbulence are calculated using synthetic spectra. The results are compared with previous analyses made with spectra taken using the REOSC echelle spectrograph at CASLEO. With this method we make better determinations of abundances and microturbulence, and identify new chemical elements.
Velocity determination from velocity spectra
Yang, Sung Jin
. correction values, ms Sp no. correction values, ms 1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 source 30 30 32 27 27 27 33 33 32 29 25 25 29 27 25 25 25 26 31 40 23 23... Figure 14. CDP gathers at some shot points. . . Figure 15. Velocity spectra at SP 12. 5 and 20. 5. . 30 Figure 16. Velocity spectra at SP 28. 5 and 39. . 31 Figure 17. Velocity spectra at SP 43 and 52. . Figure 18. Stacked section. 37 Figure 19...
Raman spectra of inorganic ions
NASA Astrophysics Data System (ADS)
Degen, I. A.; Newman, G. A.
This paper contains the Raman spectra of 79 inorganic salts and sulphur which may be used as an aid in qualitative inorganic analyses. These were obtained some years ago by conventional Raman spectroscopy. No such collection exists and the order of the reference spectra is identical to those in a collection of IR spectra. A table of characteristic frequencies for 17 polyatomic ions is given. These data have increased relevance following the emergence of FT-Raman as a rapid and efficient modern technique.
New Laboratory Spectra of Isolated ?-SiC Nanoparticles: Comparison with Spectra Taken by the Infrared Space Observatory
NASA Astrophysics Data System (ADS)
Cl�ment, D.; Mutschke, H.; Klein, R.; Henning, Th.
We present new laboratory infrared spectra of matrix-isolated ?-SiC nanoparticles, which perfectly match the band profile of the 11+ ?m feature observed in carbon stars. The new laboratory spectra differ in the shape of the band profile from former measurements of SiC nanoparticles thanks to the matrix-isolation technique which allows to obtain spectra of nonagglomerated particles. The final spectra are corrected for the influence of the surrounding medium (argon-matrix) by a computational technique proposed by Papoular et al. (1998). Furthermore, we study the influence of nitrogen incorporation into the SiC lattice, which introduces a strong near-infrared absorption owing to surface-plasmon excitation (Mutschke et al. 1999). Our laboratory spectra are compared with Infrared Space Observatory observations of several carbon stars showing an 11 ?m feature either in emission or in absorption. We discuss the implications of the new laboratory results for the interpretation of the spectra of carbon stars. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the UK) and with the participation of ISAS and NASA. The SWS is a joint project of SRON and MPE.
HF Accelerated Electron Fluxes, Spectra, and Ionization
NASA Astrophysics Data System (ADS)
Carlson, Herbert C.; Jensen, Joseph B.
Wave particle interactions, an essential aspect of laboratory, terrestrial, and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich in Usp Fizicheskikh Nauk 177(11):1145-1177, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al. in J Atmos Terr Phys 44:1089-1100, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~eV, but instead to -100 times thermal energy (10 s of eV), as a consequence of inelastic collision effects on electron transport. Gurevich et al (J Atmos Terr Phys 47:1057-1070, 1985) quantified the theory of this transport effect. Merging experiment with theory in plasma physics and aeronomy, enabled prediction (Carlson in Adv Space Res 13:1015-1024, 1993) of creating artificial ionospheres once ~GW HF effective radiated power could be achieved. Eventual confirmation of this prediction (Pedersen et al. in Geophys Res Lett 36:L18107, 2009; Pedersen et al. in Geophys Res Lett 37:L02106, 2010; Blagoveshchenskaya et al. in Ann Geophys 27:131-145, 2009) sparked renewed interest in optical inversion to estimate electron spectra in terrestrial (Hysell et al. in J Geophys Res Space Phys 119:2038-2045, 2014) and planetary (Simon et al. in Ann Geophys 29:187-195, 2011) atmospheres. Here we present our unpublished optical data, which combined with our modeling, lead to conclusions that should meaningfully improve future estimates of the spectrum of HF accelerated electron fluxes. Photometric imaging data can significantly improve detection of emissions near ionization threshold, and confirm depth of penetration of accelerated electrons many km below the excitation altitude. Comparing observed to modeled emission altitude shows future experiments need electron density profiles to derive more accurate HF electron flux spectra.
Hu Renyu; Seager, Sara [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ehlmann, Bethany L., E-mail: firstname.lastname@example.com [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable via prominent Si-O features in the thermal emission bands of 7-13 {mu}m and 15-25 {mu}m. The variation of brightness temperature due to the silicate features can be up to 20 K for an airless Earth analog, and the silicate features are wide enough to be distinguished from atmospheric features with relatively high resolution spectra. The surface characterization thus provides a method to unambiguously identify a rocky exoplanet. Furthermore, identification of specific rocky surface types is possible with the planet's reflectance spectrum in near-infrared broad bands. A key parameter to observe is the difference between K-band and J-band geometric albedos (A{sub g}(K) - A{sub g}(J)): A{sub g}(K) - A{sub g}(J) > 0.2 indicates that more than half of the planet's surface has abundant mafic minerals, such as olivine and pyroxene, in other words primary crust from a magma ocean or high-temperature lavas; A{sub g}(K) - A{sub g}(J) < -0.09 indicates that more than half of the planet's surface is covered or partially covered by water ice or hydrated silicates, implying extant or past water on its surface. Also, surface water ice can be specifically distinguished by an H-band geometric albedo lower than the J-band geometric albedo. The surface features can be distinguished from possible atmospheric features with molecule identification of atmospheric species by transmission spectroscopy. We therefore propose that mid-infrared spectroscopy of exoplanets may detect rocky surfaces, and near-infrared spectrophotometry may identify ultramafic surfaces, hydrated surfaces, and water ice.
Theoretical Spectra of Unmagnetized Neutron Stars
NASA Astrophysics Data System (ADS)
Joss, Paul C.; Madej, Jerzy
We have developed new models for the atmospheres of unmagnetized or weakly magnetized (B <= 1010 G) neutron stars with effective temperatures, Teff, in the range of 4� 106 K <= Teff <= 1� 107 K. Our model calculations include a full and accurate treatment of Compton scattering effects. We consider both pure hydrogen/helium atmospheres and atmospheres containing substantial amounts of iron (i.e., iron abundances at least as high as the solar value). Using our model atmospheres, we are able to determine the thermal X-ray emission spectrum of an unmagnetized neutron star as a function of Teff, surface gravity, and atmospheric chemical composition. We find, in particular, that the spectra of unmagnetized neutron stars with iron-rich atmospheres will feature absorption lines with complex structure that can, in principle, be at least partially resolved in observations that utilize the Chandra transmission gratings. We also find that the spectra of iron-rich atmospheres exhibit substantial flux deficits, relative to the spectra of hydrogen/helium atmospheres or simple blackbodies, at photon energies higher than the bound-free absorption edges of lithium-like and beryllium-like ions of iron at ~2 keV. This latter result provides a method of determining the presence and abundance of iron and/or other heavy elements in a neutron star atmosphere, without the need to resolve individual spectral lines. As described in a companion paper (Stage and Joss, these proceedings), we are currently using our results to fit Chandra observations of the point source in Cassiopeia A and other possible cases of thermal radiation by weakly magnetized neutron stars. This work was supported in part by the National Aeronautics and Space Administration under contract NAS8-38249 and by the Polish Committee for Scientific Research under grant No. 2 P03D 013 19.
An atlas of selected calibrated stellar spectra
NASA Technical Reports Server (NTRS)
Walker, Russell G.; Cohen, Martin
Five hundred and fifty six stars in the IRAS PSC-2 that are suitable for stellar radiometric standards and are brighter than 1 Jy at 25 microns were identified. In addition, 123 stars that meet all of our criteria for calibration standards, but which lack a luminosity class were identified. An approach to absolute stellar calibration of broadband infrared filters based upon new models of Vega and Sirius due to Kurucz (1992) is presented. A general technique used to assemble continuous wide-band calibrated infrared spectra is described and an absolutely calibrated 1-35 micron spectrum of alpha(Tau) is constructed and the method using new and carefully designed observations is independently validated. The absolute calibration of the IRAS Low Resolution Spectrometer (LRS) database is investigated by comparing the observed spectrum of alpha(Tau) with that assumed in the original LRS calibration scheme. Neglect of the SiO fundamental band in alpha(Tau) has led to the presence of a specious 'emission' feature in all LRS spectra near 8.5 microns, and to an incorrect spectral slope between 8 and 12 microns. Finally, some of the properties of asteroids that effect their utility as calibration objects for the middle and far infrared region are examined. A technique to determine, from IRAS multiwaveband observations, the basic physical parameters needed by various asteroid thermal models that minimize the number of assumptions required is developed.
Are PAH molecules the carriers of Unidentified Infrared Emission bands?
NASA Astrophysics Data System (ADS)
Kwok, Sun; Zhang, Yong
Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.
Turning cool star X-ray spectra upside down
K. Werner; J. J. Drake
H1504+65 is a young white dwarf with an effective temperature of 200,000 K and is the hottest post-AGB star ever analysed with detailed model atmospheres. Chandra LETG+HRC-S spectra have revealed the richest X-ray absorption line spectrum recorded from a stellar photosphere to date. The line forming regions in this extremely hot photosphere produce many transitions in absorption that are also observed in emission in cool star coronae. We have performed a detailed comparison of Chandra spectra of H1504+65 with those of Procyon and alpha Cen A and B. State of the art non-LTE model spectra for the hot white dwarf have enabled us to identify a wealth of absorption lines from highly ionised O, Ne and Mg. In turn, these features have allowed us to identify coronal lines whose origins were hitherto unknown.
Determination of parameters of deep level defects from numerical fit of deep level transient spectroscopy spectra: Analysis of accuracy and sensitivity to noise
A. A. Istratov; H. Hieslmair; C. Flink; E. R. Weber
The numerical fit of deep level transient spectroscopy (DLTS) spectra, used primarily to analyze complex DLTS spectra, is evaluated in terms of the accuracy of measuring deep levels and the sensitivity to noise. It is shown that by using numerical fit of DLTS spectra, the uncertainties in the emission activation energy and the capture cross section of deep level defects
Principal Component Analysis of Gamma-Ray Bursts' Spectra
Z. Bagoly; I. Horvath; L. G. Balazs; L. Borgonovo; S. Larsson; A. Meszaros; F. Ryde
Principal component analysis is a statistical method, which lowers the number of important variables in a data set. The use of this method for the bursts' spectra and afterglows is discussed in this paper. The analysis indicates that three principal components are enough among the eight ones to describe the variablity of the data. The correlation between spectral index alpha and the redshift suggests that the thermal emission component becomes more dominant at larger redshifts.
Exciton Polarons of Molecular Crystal Model. II. Optical Spectra
Hitoshi Sumi
Absorption and emission spectra of excitons interacting with optical or intramolecular vibrations are calculated with the dynamical coherent-potential approximation proposed previously. Investigations are made for various situations to which limiting concepts of nearly-free, self-trapped and vibronic excitons are not applicable straightforwardly. An interpretation is proposed that the absorption structure of alkali halides around the exciton peak originates from a situation
Liquid crystal as laser medium with tunable gain spectra.
Blinov, L M; Cipparrone, G; Lazarev, V V; Pagliusi, P; Rugiero, T
Amplified spontaneous emission intensity and gain spectra in polarized light have been measured in a dye doped nematic liquid crystal for different orientation of its optical axis and pump intensity. A possibility for switching the gain of the liquid crystal by an external electric field is shown experimentally. The liquid crystal materials with field controlled gain can be used in microlasers and light micro-amplifiers in both planar and waveguiding geometry. PMID:18545366
5-14 ?m Spitzer spectra of Themis family asteroids
NASA Astrophysics Data System (ADS)
Licandro, J.; Hargrove, K.; Kelley, M.; Campins, H.; Ziffer, J.; Al�-Lagoa, V.; Fern�ndez, Y.; Rivkin, A.
Context. The Themis collisional family is one of the largest and best established families in the main belt. Composed of primitive asteroids, there is evidence that water is likely present in a large fraction of its members, either in aqueously altered silicates or in water ice reservoirs. The study of the abundance of water in the outer asteroid belt is important as it may be linked to the origin of Earth's water. Studying the Themis family can also help to constrain the compositional and thermal environment in the region of the solar nebula where these asteroids formed. Aims: Our aim is to constrain the composition and thermal properties of the surfaces of several Themis family asteroids. Methods: We present 5-14 ?m spectra of 8 Themis family asteroids observed with Spitzer: (222) Lucia, (223) Rosa, (316) Goberta, (383) Janina, (468) Lina, (492) Gismonda, (515) Athalia, and (526) Jena. We determine their diameters, geometric albedos and beaming parameters using the near-Earth asteroid thermal model. Their emissivity spectra are studied in order to determine if they exhibit an emission plateau from 9 to 12 ?m which has been observed in other primitive asteroids and attributed to fine-grained silicates (the Si-O stretch fundamental). Results: The derived mean albedo of our sample of Themis family asteroids is bar pV = 0.07 � 0.02 = 0.07 � 0.02, and the mean beaming parameter is bar ? = 1.05 � 0.10. The derived bar ? value is close to unity, which implies that the infrared beaming is not significant, there is likely little night-side emission from the asteroids, and the thermal inertia is probably low. The emissivity spectra of at least 5 of our 8 asteroids show a 9-12 ?m emission plateau with spectral contrast of 2-4%, similar but smaller than that observed in the spectra of Trojan asteroids and cometary dust. The plateau may be due to the surfaces having either small silicate grains embedded in a relatively transparent matrix, or from a very under-dense (fairy-castle) surface structure. Conclusions: The surfaces of a large fraction of Themis family asteroids with D 50 km are covered by a fine grained silicate mantle as observed on Trojan asteroids of similar or larger size. The lower amplitude of the silicate emission in Themis family asteroids spectra (2-4%) with respect to that of Trojan asteroids (10-15%) could be attributed to larger dust particles, a slightly denser structure, or a lower silicate dust fraction.
NASA Astrophysics Data System (ADS)
Asty, M.
A review of acoustic emission methods is presented. These are considered to be a valuable nondestructive technique to evaluate the effect of stresses on materials. The nature of acoustic emissions are described. Techniques which are most suited to industrial applications are emphasized. Codification attempts by ASME and ASTM are discussed.
What can we learn from quasar absorption spectra?
NASA Astrophysics Data System (ADS)
Gallerani, Simona
We analyze optical-near infrared spectra of a large sample of quasars at high redshift with the aim of investigating both the cosmic reionization history at z ~ 6 and the properties of dust extinction at z > 4. In order to constrain cosmic reionization, we study the transmitted flux in the region blueward the Lya emission line in a sample of 17 quasars spectra at 5.7 <= zem <= 6.4. By comparing the properties of the observed spectra with the results of a semi-analytical model of the Ly? forest we find that actual data favor a model in which the Universe is highly ionized at z ~ 6, thus being consistent with an epoch of reionization at higher redshifts. For what concerns the study of the high-z dust, we focus our attention on the region redward the Lya emission line of 33 quasars at 4 <= zem <= 6.4. We compute simulated dust-absorbed quasar spectra by taking into account a large grid of extinction curves. We find that the SMC extinction curve, which has been shown to reproduce the dust reddening of most quasars at z < 4, is not a good prescription for describing dust extinction also at higher redshifts.
Analytic and numerical calculations of quantum synchrotron spectra from relativistic electron distributions
NASA Technical Reports Server (NTRS)
Brainerd, J. J.; Petrosian, V.
Calculations are performed numerically and analytically of synchrotron spectra for thermal and power-law electron distributions using the single-particle synchrotron power spectrum derived from quantum electrodynamics. It is found that the photon energy at which quantum effects appear is proportional to temperature and independent of field strength for thermal spectra; quantum effects introduce an exponential roll-off away from the classical spectra. For power law spectra, the photon energy at which quantum effects appear is inversely proportional to the magnetic field strength; quantum effects produce a steeper power law than is found classically. The results are compared with spectra derived from the classical power spectrum with an energy cutoff ensuring conservation of energy. It is found that an energy cutoff is generally an inadequate approximation of quantum effects for low photon energies and for thermal spectra, but gives reasonable results for high-energy emission from power-law electron distributions.
Spitzer Spectra of Magellanic Cloud PNe
L. Stanghellini; P. Garcia Lario; A. Manchado; J. V. Perea Calderon; D. A. Garcia-Hernandez; R. A. Shaw; E. Villaver
Planetary nebulae (PNe) in the Magellanic Clouds (LMC, SMC) offer a unique opportunity to study both the population and evolution of low- and intermediate-mass stars in an environment which is free of the distance scale bias that hinder Galactic PN studies. The emission shown by PNe in the 5-40 $\\mu$m range is characterized by the presence of a combination of solid state features (from the dust grains) and nebular emission lines over-imposed on a strong dust continuum. We acquired low resolution IRS spectroscopy of a selected sample of LMC and SMC PNe whose morphology, size, central star brightness, and chemical composition are known. The data have been acquired and reduced, and the IRS spectra show outstanding quality as well as very interesting features. The preliminary analysis presented here allows to determine strong correlations between gas and dust composition, and nebular morphology. More detailed analysis in the future will deepen our knowledge of mass-loss mechanism, its efficiency, and its relation to PN morphology.
Short Time-Scale Emission Line Variations in Mira B
NASA Astrophysics Data System (ADS)
Chamber, H. L., II; Moffett, T. J.; Barnes, T. G., III
Spectra of Mira were taken at McDonald Observatory near Mira A minimum in December 1975 using an image tube spectrograph. Series of spectra on a two to three minute time-scale show significant line strength variations in the emission lines associated with Mira B.
Emission Line Studies of the Supernova Remnant IC443
S. B. Cooper; W. W. Craig; S. M. Kahn; C. J. Hailey; J. P. Brodie
We present preliminary results from a comprehensive study of optical emission lines in the intermediate age supernova remnant IC443. This remnant has been well-studied at all wavelengths in the bright northeast limb where the remnant is interacting with a molecular cloud. We have obtained ~ 60 spectra at positions throughout the remnant. The spectra were obtained with the Automated Multi
Mid infrared emission of nearby Herbig Ae/Be stars
R. Siebenmorgen; T. Prusti; A. Natta; Th. Mueller
We present mid IR spectro-photometric imaging of a sample of eight nearby ($D \\leq 240$pc) Herbig Ae/Be stars. The spectra are dominated by photospheric emission (HR6000), featureless infrared excess emission (T~Cha), broad silicate emission feature (HR5999) and the infrared emission bands (HD 97048, HD 97300, TY~CrA, HD 176386). The spectrum of HD179218 shows both silicate emission and infrared emission bands (IEB). All stars of our sample where the spectrum is entirely dominated by IEB have an extended emission on scales of a few thousand AU ($\\sim 10''$). We verify the derived source extension found with ISOCAM by multi--aperture photometry with ISOPHT and compare our ISOCAM spectral photometry with ISOSWS spectra.
XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Active Galactic Nuclei
Fang, Taotao; Bullock, James S; Ma, Renyi
Highly ionized, z=0 metal absorption lines detected in the X-ray spectra of background active galactic nuclei (AGNs) provide an effective method to probe the hot ($T\\sim10^6$ K) gas and its metal content in and around the Milky Way. We present an all-sky survey of the $K_{\\alpha}$ transition of the local O VII absorption lines obtained by Voigt-profile fitting archival XMM-Newton observations. A total of 43 AGNs were selected, among which 12 are BL Lac-type AGNs, and the rest are Seyfert 1 galaxies. At above the $3\\sigma$ level the local O VII absorption lines were detected in 21 AGNs, among which 7 were newly discovered in this work. The sky covering fraction, defined as the ratio between the number of detections and the sample size, increases from at about 40% for all targets to 100% for the brightest targets, suggesting a uniform distribution of the O VII absorbers. We correlate the line equivalent width with the Galactic coordinates and do not find any strong correlations between these quantities. Some AG...
Validation of aggregate delayed neutron spectra calculated from precursor data
Brady, M. C.; England, T. R. [Oak Ridge National Lab., TN (USA); ,
An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delayed neutron emission probabilities, and spectra for 271 precursors. These data have been used to calculate the aggregate behavior of delayed neutrons following a fission event in 43 fissioning systems. Least-squares techniques were used to produce fitted decay constants and abundances in the conventional six-group formalism from these calculated activity curves. A consistent set of six-group spectra have also been calculated for each of the fissioning systems. Recent measurements at the University of Lowell have produced measured energy spectra for delayed neutrons following the thermal fission (T) of {sup 235}U and {sup 239}Pu, and the fast fission (F) of {sup 238}U. These measured spectra provide data that may be used to validate the precursor data base and the fitted six-group data. This summary presents results of this validation effort. Both the individual precursor data and the six-group data have been used to calculate aggregate equilibrium spectra for {sup 235}U(T), {sup 238}U(F), and {sup 239}Pu(T) via summation techniques. The important precursors in each case are identified, and the status of their data reviewed. 8 refs., 3 figs., 3 tabs.
The composite load spectra project
NASA Technical Reports Server (NTRS)
Newell, J. F.; Ho, H.; Kurth, R. E.
Probabilistic methods and generic load models capable of simulating the load spectra that are induced in space propulsion system components are being developed. Four engine component types (the transfer ducts, the turbine blades, the liquid oxygen posts and the turbopump oxidizer discharge duct) were selected as representative hardware examples. The composite load spectra that simulate the probabilistic loads for these components are typically used as the input loads for a probabilistic structural analysis. The knowledge-based system approach used for the composite load spectra project provides an ideal environment for incremental development. The intelligent database paradigm employed in developing the expert system provides a smooth coupling between the numerical processing and the symbolic (information) processing. Large volumes of engine load information and engineering data are stored in database format and managed by a database management system. Numerical procedures for probabilistic load simulation and database management functions are controlled by rule modules. Rules were hard-wired as decision trees into rule modules to perform process control tasks. There are modules to retrieve load information and models. There are modules to select loads and models to carry out quick load calculations or make an input file for full duty-cycle time dependent load simulation. The composite load spectra load expert system implemented today is capable of performing intelligent rocket engine load spectra simulation. Further development of the expert system will provide tutorial capability for users to learn from it.
Gallery of Planetary Nebula Spectra
Karen B. Kwitter; Richard B. C. Henry
We present the Gallery of Planetary Nebula Spectra now available at http://oit.williams.edu/nebulae The website offers high-quality, moderate resolution (~7-10 A FWHM) spectra of 128 Galactic planetary nebulae from 3600-9600 A, obtained by Kwitter, Henry, and colleagues with the Goldcam spectrograph at the KPNO 2.1-m or with the RC spectrograph at the CTIO 1.5-m. The master PN table contains atlas data and an image link. A selected object's spectrum is displayed in a zoomable window; line identification templates are provided. In addition to the spectra themselves, the website also contains a brief discussion of PNe as astronomical objects and as contributors to our understanding of stellar evolution. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users: researchers might need to check the spectrum of a particular object of interest; the non-specialist astronomer might simply be interested in perusing such a collection of spectra; and finally, teachers of introductory astronomy can use this database to illustrate basic principles of atomic physics and radiation. To particularly encourage this last use, we have developed two paper-and-pencil exercises to introduce beginning astronomy students to the wealth of information that PN spectra contain.
Vanadium Oxide in the Spectra of Mira Variables
NASA Astrophysics Data System (ADS)
Castelaz, M. W.; Luttermoser, D. G.; Piontek, R. A.
Over the last three years, we have made spectroscopic measurements of twenty Mira variable stars, as a function of phase, probing their stellar atmospheres and underlying pulsation mechanisms. Measurement of variations in TiO and VO with phase can be used to help determine whether these molecular species are produced in an extended region above the layers where Balmer line emission occurs or below this shocked region. Piontek & Luttermoser (1999 IAPPPC, submitted), produce synthetic spectra for three Mira variables, R Leo, V CVn, and R CVn as a function of phase. Comparison of their synthetic spectra to our observed spectra yield the fundamental astrophysical parameters of effective temperatures and surface gravities. Spectra are synthesized with LTE stellar stmospheres code ATLAS, using the 6.6--million Indiana University atomic and molecular line dataset. Piontek & Luttermoser point out that the IU dataset does not include vanadium oxide (VO). Thus, there is a noticeable difference between the synthetic spectra and observed near-IR spectra corresponding to the B-X bands of VO (Mahanti 1935, Proc. Phys. Soc., 47, 43; Keenan & Schroeder 1952,L. W., ApJ, 115, 82). In order to incorporate the VO bands in the synthetic spectra, we need to establish tables of wavenumbers, lowest energy levels, and oscillator strengths. Producing the tables is non-trivial. Laboratory measurements of wavenumbers are used in the Just-Overlapping Line Approximation (JOLA; Tsuji 1966, PASJ, 18, 127) to calculate oscillator strengths. The JOLA technique and preliminary results will be presented. MWC greatly appreciates support from the National Science Foundation grant AST-9500756. RAP acknowledges the Southeastern Association for Research in Astronomy 1998 Summer REU program supported by the National Science Foundation and thanks DGL for being his mentor.
Magnetic Dipole Microwave Emission from Dust Grains
Draine, B T
Thermal fluctuations in the magnetization of interstellar grains will produce magnetic dipole emission at frequencies below ~100 GHz. We show how to calculate absorption and emission from small particles composed of magnetic materials. The Kramers-Kronig relations for a dusty medium are generalized to include the possibility of magnetic grains. The frequency-dependent magnetic permeability is discussed for candidate grain materials, including iron and magnetite. We calculate emission spectra for various interstellar grain candidates. While paramagnetic grains or magnetite grains cannot account for the observed "anomalous" emission from dust in the 14-90 GHz range, stronger magnetic dipole emission will result if a fraction of the grain material is ferromagnetic, as could be the case given the high Fe content of interstellar dust. The observed emission from dust near 90 GHz implies that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in "GEMS"). However, we show ...
Emission spectral characteristics of Cu, Ag, Zn, and Cd neutral atoms in a glow discharge
Yuhui Zhao; Gary Horlick
Detailed spectra highlighting the neutral atom emission characteristics (i.e. I lines) for Cu, Zn, Ag and Cd in a glow discharge device are presented in this study. A particular focus is the presentation of spectra that document the many high excitation energy neutral atom lines that are observed in these spectra. For Cu, several spectral lines originating from levels close
Correlations between mercuric iodide photoluminescence spectra and nuclear detector performance
NASA Astrophysics Data System (ADS)
Bao, X. J.; Schlesinger, T. E.; James, R. B.; Harvey, S. J.; Cheng, A. Y.; Gerrish, V.; Ortale, C.
Low temperature photoluminescence spectroscopy was performed on a variety of HgI 2 samples and also on graded HgI 2 nuclear detectors. Correlations were found between features in the photoluminescence spectra and a crystal's ability to produce high-quality detectors. The intensity of a broad emission band centered at 6200 � (designated as band 3) is weaker in crystals that yield high-quality detectors. Therefore, the defects responsible for this emission band are undesirable in the fabrication of HgI 2 nuclear detectors. The measurements also revealed that stronger emission in the exciton region (designated as band 1) is associated with crystals which produce high-quality detectors, indicating that a high degree of structural perfection is important for HgI 2 detector applications. These correlations, together with earlier results from studies of processing-induced defects, lead to suggestions regarding improvement of the manufacturing yield of high-quality HgI 2 detectors.
An Interpretation of Banded Magnetospheric Radio Emissions
NASA Technical Reports Server (NTRS)
Benson, Robert F.; Osherovich, V. A.; Fainberg, J.; Vinas, A. F.; Ruppert, D. R.; Vondrak, Richard R. (Technical Monitor)
Recently-published Active Magnetospheric Particle Tracer Explorer/Isothermal Remanent Magnetization (AMPTE/IRM) banded magnetospheric emissions, commonly referred to as '(n + 1/2)f(sub ce)' emissions where f(sub ce) is the electron gyrofrequency, are analyzed by treating them as analogous to sounder-stimulated ionospheric emissions. We show that both individual AMPTE/IRM spectra of magnetospheric banded emissions, and a statistically-derived spectra observed over the two-year lifetime of the mission, can be interpreted in a self-consistent manner. The analysis, which predicts all spectral peaks within 4% of the observed peaks, interprets the higher-frequency emissions as due to low group-velocity Bernstein-mode waves and the lower-frequency emissions as eigen modes of cylindrical-electromagnetic-plasma-oscillations. The demarcation between these two classes of emissions is the electron plasma frequency f(sub pe), where an emission is often observed. This f(sub pe), emission is not necessarily the strongest. None of the observed banded emissions were attributed to the upper-hybrid frequency. We present Alouette-2 and ISIS-1 plasma-resonance data, and model electron temperature (T(sub e)) values, to support the argument that the frequency-spectrum of ionospheric sounder-stimulated emissions is not strongly temperature dependent and thus that the interpretation of these emissions in the ionosphere is relevant to other plasmas (such as the magnetosphere) where N(sub e) and T(sub e) can be quite different but where the ratio f(sub pe)/f(sub ce) is identical.
Vibrational spectra of hexaaqua complexes
Vladimir Ivanovski; Vladimir M. Petru�evski; Bojan �optrajanov
FT-IR spectra of RbAl(SO4)2�12H2O and KAl(SO4)2�12H2O alums were investigated in the region of the ?3(SO4) mode. The spectra were analyzed at room (?293K, RT) and at low temperature (?100K, LT). The doublet arising from this mode, evident in the LT spectrum, could be attributed to either site-group or correlation-field splitting. In order to reveal its exact origin, isomorphous isolation of
Velocity determination from velocity spectra�
Yang, Sung Jin
. on from Velocity Spectra (December 1973) Sung Jin Yang, B. S. Seoul National University; Korea Directed by: Dr. Anthony F. Gangi The reflected signals on the traces of a common-depth-point (CDP) gather appear along a hyperbolic curve which is a...VELOCITY DETERMINATION FRON VELOCITY SPECTRA A Thesis by SUNG JIN YANG Submutted to the Graduate C:lleEe of Texas ASM University in partial fulfill sent of requirement for the degree of EASTER GF SCIENCE December 1973 Naj or Subject...
Broad iron K emission line and spectral variability of the Seyfert 2 galaxy IRAS 18325-5926
NASA Technical Reports Server (NTRS)
Iwasawa, K.; Fabian, A. C.; Mushotsky, R. F.; Brandt, W. N.; Awaki, H.; Kunieda, H.
A very broad iron K alpha emission line is observed in the Advanced Satellite for Cosmology and Astrophysics (ASCA) spectrum of the Seyfert 2 galaxy IRAS 18325-5926. The line profile is peaked at 6.9 keV and skewed down to 4 keV. The breadth and shift of the line energy can be interpreted by Doppler and relativistic effects in a cold accretion disk about a black hole with a intermediate inclination of between 40 and 50 deg. The steep spectral slope and the fast variability on a timescale of 10(exp 4) s are confirmed for this object. A study of spectral variability reveal that the X-ray flux change mainly occurred above 1 keV and the soft X-ray component below 1 keV appears to be less variable or constant and should lie outside of the nuclear obscuration.
The SPECTRa Project: A Wider Chemistry View
Downing, Jim; Tonge, Alan
(Controlled) public release User search tools OAI-PMH Metadata Harvesting Internet DSpace Escrow DSpace Open Computational Chemistry Calculations 2D Chemical Structures NMR Spectra 3D X-ray Structures SPECTRa Deposit Tools Create CML, InChI, metadata SPECTRa... Cotterill, Jim Downing Project Manager: Alan Tonge Library Liaison: Janet Evans, Lorraine Windsor http://www.lib.cam.ac.uk/spectra/ ...
Isochoric heating of reduced mass targets by ultra-intense laser produced relativistic electrons
Neumayer, P; Lee, H J; Offerman, D; Shipton, E; Kemp, A; Kritcher, A L; Doppner, T; Back, C A; Glenzer, S H
We present measurements of the chlorine K-alpha emission from reduced mass targets, irradiated with ultra-high intensity laser pulses. Chlorinated plastic targets with diameters down to 50 micrometers and mass of a few 10{sup -8} g were irradiated with up to 7 J of laser energy focused to intensities of several 10{sup 19} W/cm{sup 2}. The conversion of laser energy to K-alpha radiation is measured, as well as high resolution spectra that allow observation of line shifts, indicating isochoric heating of the target up to 18 eV. A zero-dimensional 2-temperature equilibration model, combined with electron impact K-shell ionization and post processed spectra from collisional radiative calculations reproduces the observed K-alpha yields and line shifts, and shows the importance of target expansion due to the hot electron pressure.
Electric quadrupole transitions in x-ray spectra: 3d transition-metal oxides
N. V. Dobrodey; Yu. V. Luniakov
The intensities of the electric quadrupole transitions in the x-ray spectra of the 3d-transition-metal monoxide diatomic molecules were calculated using the discrete variational method of the local-density approximation. The quadrupole transition intensities have been found to be negligible for the left-hand-side 3d metal oxides. It was shown that the electric quadrupole transitions can appreciably contribute to the MKbeta5 emission spectra
X-Ray Spectra of Bursting Neutron Stars and Color Temperature - Luminosity Diagram
T. Ebisuzaki; K. Nomoto
The authors calculate atmospheric models and emitted X-ray spectra for X-ray bursting neutron stars taking into account the effects of Comptonization and free-free and bound-free emission and absorption. The color temperatures obtained from the calculated X-ray spectra are higher than the effective temperatures. The theoretical color-temperature to luminosity diagram is in good agreement with the observational diagram of MXB 1636-536
Information Content of Iris Spectra
John C. Price
the number of independent variables needed to describe these broad band high spectral resolution data. The radiated power in the atmospheric window from 771 to 981 cm - was the first parameter chosen for, fitting observed spectra. At succeeding levels of analysis the residual variability (observed spectrum minus best-fit spectrum) in an ensemble of observations was partitioned into spectral eigenvectors.
Investigating the Near-Infrared Properties of Planetary Nebula II. Medium Resolution Spectra
Joseph L. Hora; William B. Latter; Lynne K. Deutsch
We present medium-resolution (R~700) near-infrared (lambda = 1 - 2.5 micron) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H I emission line-dominated PNe, H I and H_2 emission line PNe, H_2-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H_2 and continuum emission groups. Other spectral features were observed in all categories, such as continuum emission from the central star, C_2, CN, and CO emission, and warm dust continuum emission. Molecular hydrogen was detected for the first time in four PNe. An excitation analysis was performed using the H_2 line ratios for all of the PN spectra in the survey where a sufficient number of lines were observed. One unexpected result from this analysis is that the H_2 is excited by absorption of ultraviolet photons in most of the PNe surveyed, although for several PNe in our survey collisional excitation in moderate velocity shocks plays an important role. The correlation between bipolar morphology and H_2 emission has been strengthened with the new detections of H_2 in this survey.
Physics issues of gamma ray burst emissions
NASA Technical Reports Server (NTRS)
Liang, Edison
The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.
Infrared emission spectroscopic study of brucite
Ray L Frost; J. Theo Kloprogge
Both infrared absorption and emission spectroscopy have been used to assign the vibrational bands of brucite. IR absorption bands are observed in the hydroxyl stretching region at 3698 and 3248 cm?1. Low frequency bands are observed at 627, 565 and 440 cm?1. Naturally occurring brucites are contaminated with other magnesium minerals which are easily identified by the infrared spectra. Infrared
Outline Phonon spectra of graphene Raman spectra of graphene Crystal lattice dynamics
of graphene Raman spectra of graphene Phonon branches of graphene 1 acoustic flexural mode ZA 2 ZA = Dzz 12(qOutline Phonon spectra of graphene Raman spectra of graphene Crystal lattice dynamics Graphene dynamics July 11, 2013 1 / 19 #12;Outline Phonon spectra of graphene Raman spectra of graphene 1 Phonon
Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1
Greg Goldstein; David P. Huenemoerder; David Blank
High resolution spectral studies were undertaken at orbital phases 0, 0.25 and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra data. We present (a) the first detailed analysis of the multiple strong narrow emission lines present in phase 0.5 (b) an analysis of the absorption of the continuum in phase 0.5, and (c) the first detection of narrow emission and absorption lines in phase 0.25. Multiple fluorescent and H-and He-like emission lines in the band 1.6 - 20 Angstrom in eclipse are partially obscured at phase 0.25 by the X-ray continuum. The phase 0.25 spectrum displays 3 triplets, 2 with a blue-shifted resonance (r) line in absorption and the intercombination (i) and forbidden (f) lines in emission, and shows in absorption other blue-shifted lines seen in emission in eclipse. At phase 0.5 the soft X-ray continuum diminishes revealing an "eclipse-like" spectrum, however line flux values are around 13-fold those in eclipse. We conclude the narrow emission lines in Vela X-1 become apparent when the continuum is blocked from line of sight, either by eclipse or by scattering and/or absorption from a wake or cloud. The H-and He-like lines arise in warm photoionised regions in the stellar wind, while the fluorescent lines (including a Ni K alpha line) are produced in cooler clumps of gas outside these regions. Absorption of the 5-13 Angstrom continuum at phase 0.5 may be caused by an accretion wake comprised of dense stagnant photoionized plasma inside a Stromgren zone. Multiple fluorescent emission lines may be a common feature of the supergiant category of HMXBs.
Magnetic Dipole Microwave Emission from Dust Grains
B. T. Draine; A. Lazarian
Thermal fluctuations in the magnetization of interstellar grains will produce magnetic dipole emission at frequencies below ~100 GHz. We show how to calculate absorption and emission from small particles composed of magnetic materials. The Kramers-Kronig relations for a dusty medium are generalized to include the possibility of magnetic grains. The frequency-dependent magnetic permeability is discussed for candidate grain materials, including iron and magnetite. We calculate emission spectra for various interstellar grain candidates. While paramagnetic grains or magnetite grains cannot account for the observed "anomalous" emission from dust in the 14-90 GHz range, stronger magnetic dipole emission will result if a fraction of the grain material is ferromagnetic, as could be the case given the high Fe content of interstellar dust. The observed emission from dust near 90 GHz implies that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in "GEMS"). However, we show that if most interstellar Fe is in a moderately ferromagnetic material, it could contribute a substantial fraction of the observed 14-90 GHz emission, perhaps comparable to the contribution from spinning ultrasmall dust grains. The two emission mechanisms can be distinguished by measuring the emission from dark clouds. The expected polarization of magnetic dipole emission is discussed
ERIC Educational Resources Information Center
Keliher, Peter N.; And Others
Presented is a review of selected literature on emission spectrometry published during 1982 and 1983. The review is organized under these headings: books and reviews; spectral descriptions and classifications; instrumentation; standards, samples, nomenclature, calibration, calculations; excitation sources; selected applications; and meetings. (JN)
NASA Technical Reports Server (NTRS)
Rohde, John
The Emissions Reduction Project is working in close partnership with the U.S. aircraft engine manufacturers and academia to develop technologies to reduce NO, emissions by 70 percent over the LTO cycle from 1996 ICAO standards with no increase in other emission constituents (carbon monoxide, smoke, and unburned hydrocarbons) and with comparable NO, reduction during cruise operations. These technologies cannot impact the overall combustor and fuel delivery system operability, affordability or maintainability. These new combustion concepts and technologies will include lean burning combustors with higher operating gas temperatures and pressures, fuel staging, ceramic matrix composite material liners with reduced cooling air and possibly advanced controls. Improved physics-based analysis tool will be developed and validated and some longer term technologies that are more revolutionary will be assessed. These improved computational codes will provide improved design tools to increase design confidence and cut the development time to achieve major reductions in NO, emissions. Longer term, revolutionary technologies like active combustion controls, combustion from a large array of micro-injectors, electrostatic fuel injectors, fuel additives and others will be investigated and assessed through proof-of-concept testing.
Discovery of Oxygen Kalpha X-ray Emission from the Rings of Saturn
Anil Bhardwaj; Ronald F. Elsner; J. Hunter Waite, Jr.; G. Randall Gladstone; Thomas E. Cravens; Peter G. Ford
Using the Advanced CCD Imaging Spectrometer (ACIS), the Chandra X-ray Observatory (CXO) observed the Saturnian system for one rotation of the planet (~37 ks) on 20 January, 2004, and again on 26-27 January, 2004. In this letter we report the detection of X-ray emission from the rings of Saturn. The X-ray spectrum from the rings is dominated by emission in a narrow (~130 eV wide) energy band centered on the atomic oxygen K-alpha fluorescence line at 0.53 keV. The X-ray power emitted from the rings in the 0.49-0.62 keV band is 84 MW, which is about one-third of that emitted from Saturn disk in the photon energy range 0.24-2.0 keV. Our analysis also finds a clear detection of X-ray emission from the rings in the 0.49-0.62 keV band in an earlier (14-15 April, 2003) Chandra ACIS observation of Saturn. Fluorescent scattering of solar X-rays from oxygen atoms in the H2O icy ring material is the likely source mechanism for ring X-rays, consistent with the scenario of solar photo-production of a tenuous ring oxygen atmosphere and ionosphere recently discovered by Cassini.
Helium emission in the spectrum of Kappa Canis Majoris
J. D. R. Bahng; E. Hendry
Coude spectra of kappa CMa in the red region showed H alpha and He 1 lambda lambda 5876,6678 in emission. Each of the lines had two emission components, but the helium lines had no detectable absorption feature in between. While the H alpha emission peaks were separated by 160 km\\/sec, the helium lines were separated by 400 km\\/sec. A simple
NaI detector neutron activation spectra for PGNAA applications
Gardner; El; Zheng; Hayden; Mayo
When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known. PMID:11003483
Emission-line regions of quasars
Kwan, J.
The emission spectra of quasars prominently consist of broad permitted and semiforbidden lines of full width at half-maximum. It has been suggested that the emission lines are produced by photoionization of surrounding gas by the strong central continuum. The power-law UV continuum not only provides a convenient energy source for the line emission, but also creates the wide range of observed high and low ionization species. Theoretical photoionization models have produced the observed line intensities. Two conditions make the photoionization models of the quasar emission-line clouds different from standard nebular calculations: the strong X-ray luminosity of the quasar, and the relatively high density of the quasar emission-line cloud. Among the proposed kinematic models of the broad line gas are the outflow of matter being accelerated by radiation pressure or by a hot wind, as well as ballistic outflow of matter, matter in circular orbits, and matter in parabolic orbits. 41 references.
Hierarchical analysis of molecular spectra
Davis, M.J.
A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obtain any other way as well as an understanding of intramolecular energy transfer time scales, mechanisms, and pathways. The methodology has been applied to several problems: transition state spectroscopy, intramolecular energy transfer in highly excited molecules, high-resolution overtone spectroscopy, and the nature of the classical-quantum correspondence when there is classical chaos (``quantum chaos``).
Spectra of Modular Random Graphs
Guler Ergun; R. Kuehn
We compute spectra of symmetric random matrices defined on graphs exhibiting a modular structure. Modules are initially introduced as fully connected sub-units of a graph. By contrast, inter-module connectivity is taken to be incomplete. Two different types of inter-module connectivity are considered, one where the number of intermodule connections per-node diverges, and one where this number remains finite in the
Wavelet spectra of JACEE events
Suzuki, N; Ohsawa, A; Suzuki, Naomichi; Biyajima, Minoru; Ohsawa, Akinori
Pseudo-rapidity distributions of two high multiplicity events Ca-C and Si-AgBr observed by the JACEE are analysed by the wavelet transform. Wavelet spectra of those events are calculated and compared with the simulation calculations. The wavelet spectrum of Ca-C event somewhat resembles to that simulated with the uniform random numbers. That of Si-AgBr event is not reproduced by simulation calculations with Poisson random numbers, uniform random numbers, or a p-model.
Diagram spaces and symmetric spectra
Steffen Sagave; Christian Schlichtkrull
We present a general homotopical analysis of structured diagram spaces and discuss the relation to symmetric spectra. The main motivating examples are the I-spaces, which are diagrams indexed by finite sets and injections, and J-spaces, which are diagrams indexed by the Grayson-Quillen construction on the category of finite sets and bijections. We show that the category of I-spaces provides a
Modeling of skin reflectance spectra
Igor V. Meglinsky; Stephen J. Matcher
We use the optical\\/near-infrared (NIR) reflectance spectroscopy to non-invasively measure the hemoglobin saturation in living human skin. The difficulties in clinical application of this technique for skin tissue oxygenation monitoring are due to the complexity of extracting the information of chromophores distribution and their concentrations from the reflectance spectra in case of multiple scattering of light. We have developed a
Optical Spectra of Triggered Lightning
NASA Astrophysics Data System (ADS)
Walker, T. D.; Biagi, C. J.; Hill, J. D.; Jordan, D. M.; Uman, M. A.; Christian, H. J., Jr.
In August 2009, the first optical spectra of triggered lightning flashes were acquired. Data from two triggered lightning flashes were obtained at the International Center for Lightning Research and Testing in north-central Florida. The spectrometer that was used has an average dispersion of 260 �/mm resulting in an average resolution of 5 � when mated to a Photron (SA1.1) high-speed camera. The spectra captured with this system had a free spectral range of 3800-8000 �. The spectra were captured at 300,000 frames per second. The spectrometer's vertical field of view was 3 m at an altitude 50 m above the launch tower, intended to view the middle of the triggering wire. Preliminary results show that the copper spectrum dominated the earliest part of the flash and copper lines persisted during the total lifetime of the detectable spectrum. Animations over the lifetime of the stroke from the initial wire illumination to multiple return strokes show the evolution of the spectrum. In addition, coordinated high speed channel base current, electric field and imagery measurements of the exploding wire, downward leaders, and return strokes were recorded. Quantitative analysis of the spectral evolution will be discussed in the context of the overall flash development.
Far-UV FUSE spectra of peculiar magnetic cataclysmic variables
Martine Mouchet; Jean-Marc Bonnet-Bidaud; Evelyne Roueff; Meil Abada-Simon; Klaus Beuermann; Domitilla de Martino; Jean-Michel Desert; Roger Ferlet; Robert Fried; Boris Gaensicke; Steve Howell; Koji Mukai; Delphine Porquet; Paula Szkody
We present far-UV spectra of the three magnetic cataclysmic variables (MCVs) BY Cam, V1309 Ori and AE Aqr obtained with the FUSE satellite. These MCVs have revealed strongly unusual NV and CIV UV resonance lines. The FUSE spectra exhibit broad OVI lines as well as a strong NIII line at 991A, while the CIII 1175A line is nearly absent, supporting non-solar CNO abundances of the accreting matter in these sources. The spectrum of BY Cam shows molecular H2 lines which might be of circumstellar nature. The flaring activity of AE Aqr is also observed in the far-UV range. The radial velocities of the broad OVI components in AE Aqr are orbitally modulated and would indicate an emission region close to the magnetosphere.
[Fluorescence spectra of Dichroa febrifuga aqueous extraction].
Zhang, Ying-hua; Shi, Xun-li; Liu, Ya-lan; Liu, Cui-ge; Wei, Yong-ju
Fluorescence spectra of chang shan (Dichroa febrifuga Lour) aqueous extraction were studied. In the three-dimensional fluorescence contour spectrum, three fluorescence peaks of quinazoline alkaloids, which are the active components of chang shan, were observed. The excitation wavelengths of the peaks were 235, 270 and 320 nm, respectively, and the emission wavelength of all the peaks was 430 nm. Three-dimensional fluorescence contour spectrum is the very image of fingerprint, suitable for qualitative identification of traditional Chinese medicine. In the range of pH 3 to pH 6, the fluorescence spectrum of chang shan aqueous extractions changes with the variation in pH value. The reason for this spectral change might be the protonation of N-1 in quinazolone ring of beta-dichroine (febrifugine) molecule. There is an excellent linear relationship between the fluorescence intensity and the concentration of chang shan under nearly neutral conditions, thereby a quantitative method for the determination of quinazoline alkaloids may be established. PMID:17514972
Near-infrared spectra of compact stellar wind sources at the Galactic center
NASA Technical Reports Server (NTRS)
Libonate, S.; Pipher, J. L.; Forrest, W. J.; Ashby, M. L. N.
We present high- and low-resolution, H- and K-band spectra on nine compact 2.2 micrometers Galactic center sources in which we clearly detect He I 2.058 micrometers emission, including the AF source, IRS 13, IRS 1W, IRS 16NE, IRS 16NW, IRS 16C, IRS 16SW, IRS 34, and IRS 6E. We have also obtained comparison spectra of both a luminous blue variable (LBV) and a WR star (P Cygni and HD 192163, respectively). Our H- and K-band spectrum of the LBV P Cygni strongly resembles the near-infrared spectra of known WN9/Ofpe stars. Our spectra of the Galactic center sources share many characteristics in common with our spectrum of P Cygni. The spectra all show emission lines of H I and He I with large He I/H line flux ratios. Some have permitted and forbidden lines of Fe II. Brackett line widths and ratios indicate the presence of strong stellar winds. In contrast to the spectrum of the WR star, none of the Galactic center sources show evidence of He II emission lines in their spectra, suggesting that none of the Galactic center sources are WR stars. Our high-resolution H-band spectrum of the AF source differs from previously published low-resolution H-band spectra in that it is rich in emission lines. Furthermore, we find two distinct spectral components to the AF source separated in space by a few arcseconds. We identify both the emission-line component of the AF source and an exciting source of IRS 13 as an LBV or WN9/Ofpe star. Our results, when combined with the results of others, also suggest that IRS 16NE, IRS 16C, IRS 16NW, IRS 34, and a component of IRS 6E are early-type, emission-line stars. The argument for IRS 16SW, however, is less compelling. We find no evidence for a compact He I emission-line source at IRS 1W. This result contradicts previous findings, suggesting that the He I source at IRS 1W may be variable. If the He I lines in IRS 1W are truly variable, a stellar component of IRS 1W may be an LBV, because LBVs are known to have variable line emission on short timescales. The nine Galactic center wind sources appear to contribute a significant fraction of the total luminosity of the central few parsecs of the Galaxy.
Linsky, Jeffrey L.
1 MONITORING ALTAIR'S FAR-ULTRAVIOLET EMISSION LINES FOR VARIABILITY OVER A STELLAR ROTATION PERIOD heated by acoustic waves. Existing FUSE spectra of Altair show that the O VI and C III emission lines rotation of the star. We present a new long (27 ksec) FUSE observation of Altair, and explore emission line
Ultraviolet fluorescence excitation and emission spectroscopy of marine algae and bacteria
Stephan Determann; J�rg M. Lobbes; Rainer Reuter; J�rgen Rullk�tter
Ultraviolet (UV) excitation and emission spectra of cultures of marine bacteria and phytoplankton were investigated. The intensity of the emission band at 340 nm wavelength (?ex=230 nm) is compared with cell number and protein content, and specific efficiencies are derived. Another weak emission band at 305 nm is found with most phytoplankton species. The same fluorescence signatures are observed with
Infrared Spectra of Polycyclic Aromatic Hydrocarbons (PAHs)
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Bakes, E. L. O.
We have computed the synthetic infrared spectra of some polycyclic aromatic hydrocarbons containing up to 54 carbon atoms. The species studied include ovalene, circumcoronene, dicoronylene, and hexabenzocoronene. We report spectra for anions, neutrals, cations, and multiply charged cations.
First Hard X-Ray Detection of the Non-Thermal Emission Around the Arches Cluster: Morphology and Spectral Studies With NuSTAR
NASA Technical Reports Server (NTRS)
Krivonos, Roman A.; Tomsick, John A.; Bauer, Franz E.; Baganoff, Frederick K.; Barriere, Nicolas M.; Bodaghee, Arash; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Grefenstette, Brian W.; Hailey, Charles J.; Harrison, Fiona A.; Hong, JaeSub; Madsen, Kristin K.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Zhang, William W.
The Arches cluster is a young, densely packed massive star cluster in our Galaxy that shows a high level of star formation activity. The nature of the extended non-thermal X-ray emission around the cluster remains unclear. The observed bright Fe K(alpha) line emission at 6.4 keV from material that is neutral or in a low ionization state can be produced either by X-ray photoionization or by cosmic-ray particle bombardment or both. In this paper, we report on the first detection of the extended emission around the Arches cluster above 10 keV with the NuSTAR mission, and present results on its morphology and spectrum. The spatial distribution of the hard X-ray emission is found to be consistent with the broad region around the cluster where the 6.4 keV line is observed. The interpretation of the hard X-ray emission within the context of the X-ray reflection model puts a strong constraint on the luminosity of the possible illuminating hard X-ray source. The properties of the observed emission are also in broad agreement with the low-energy cosmic-ray proton excitation scenario. Key words: cosmic rays - Galaxy: center - ISM: general - X-rays: individual (Arches cluster)
Optimal Estimation Retrievals of CO2 from AIRS spectra
NASA Astrophysics Data System (ADS)
Irion, F. W.; Kulawik, S. S.; Kahn, B. H.; Worden, J.; Bowman, K. W.; Fishbein, E.
Since September 2002, the Atmospheric Infrared Sounder (AIRS) on the EOS-Aqua platform has globally observed atmospheric profile information from nadir viewing of infrared emittance. Selecting cloud-free spectra over ocean, we apply an optimal estimation algorithm, similar to that used for the Tropospheric Emission Spectrometer (TES), to simultaneously retrieve profiles of CO2, water vapor, ozone, temperature and ocean skin temperature. Preliminary results and validation over the Western Pacific are presented, showing good correlation with seasonal variation and long-term increase of CO2 as determined by in-situ aircraft measurements.
High Resolution Spectra of Novae and the Quadratic Zeeman Effect
Robert Williams; Elena Mason
High resolution spectra of novae after outburst reveal distinctive characteristics in the line profiles and intensities. The higher Balmer lines are often broader than the lower members of the series, and the relative profiles and intensities of the [O I] \\lambda\\lambda6300, 6364 doublet differ from normal values. We suggest these features may be caused by the Quadratic Zeeman Effect from magnetic fields exceeding B=10^6 gauss. Taken together the emission and absorption lines point to multiple origins for the ejecta on both the erupting white dwarf and the cool secondary star.
Angular Power Spectra of the COBE DIRBE Maps
Edward L. Wright
The angular power spectra of the infrared maps obtained by the DIRBE (Diffuse InfraRed Background Experiment) instrument on the COBE satellite have been obtained by two methods: the Hauser-Peebles method previously applied to the DMR maps, and by Fourier transforming portions of the all-sky maps projected onto a plane. The two methods give consistent results, and the power spectrum of the high-latitude dust emission is C_\\ell \\propto \\ell^{-3} in the range 2 < \\ell < 300.
Mass Spectra Alignments and their Significance
Lonardi, Stefano
Mass Spectra Alignments and their Significance Sebastian B¨ocker1, Hans-Michael Kaltenbach2 1 Research, Universit¨at Bielefeld B¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass Spectrometry in Proteomics Protein
Characterization of the Effects of Precursor Mineralogy on Hematite Spectra: Application to Martian Hematite Mineralization
NASA Technical Reports Server (NTRS)
Glotch, Timothy D.; Morris, Richard V.; Sharp, Thomas G.; Christensen, Philip R.
The Thermal Emission Spectrometer (TES) instrument aboard Mars Global Surveyor discovered several isolated deposits of gray, crystalline hematite in Sinus Meridiani, Aram Chaos, and Valles Marineris. A variety of formation mechanisms has been proposed for the martian hematite deposits, including aqueous and nonaqueous processes. Comparison of the average Sinus Meridiani hematite spectrum measured by TES to laboratory emissivity spectra for a variety of naturally occurring hematites shows small but potentially important differences. In particular, the emissivity minimum at 300 and 445/cm in the Sinus Meridiani (SM) spectrum is displaced 10-25/cm to lower frequencies compared to some natural hematite samples. In addition, these bands in the TES data are narrower than the broad bands seen in many natural hematite spectra. These differences may imply that the natural variability of hematite spectra has not been fully characterized, especially with respect to the reaction pathway (precursor mineralogy and temperature of hematite formation) and crystal morphology. Here, we describe the thermal infrared spectral characteristics of several series of synthetic hematite samples derived by direct precipitation, dehydroxylation of fine-grained goethite and the oxidation of magnetite. Several natural hematite sample spectra are also presented for comparison. Transmission electron microscopy (TEM) and Mossbauer spectral analyses of selected samples were performed in order to help determine the causes of the changes seen in the infrared spectra.
Xanthone. II. Vibronic coupling analysis from high resolution phosphorescence spectra
NASA Astrophysics Data System (ADS)
Griesser, Hans J.; Bramley, Richard
High resolved phosphorescence spectra of xanthone have been recorded in four host matrices in order to study vibronic coupling between the lowest tripl origin in all hosts, and the energetically close-lying second triplet state T 2, which is of n?* orbital origin. In three hosts, there is thermall to phosphorescence from T 1. Vibrational analyses of the two emissions are reported. The vibrational structure of both emissions depends little on t vibronic mixing between the lowest two triplet states is weak, in spite of the small energy separation in some hosts. The importance of the different i 1 and its sublevels is discussed, and it is concluded that across energy separations smaller than about 200 cm -1 spin�orbit mixing is more orbital mixing between the 3??* and 3n?* configurations of xanthone.
Cause of the localized maximum of X-ray emission in the morning sector: A comparison with electron measurements
Bergen, Universitetet i
and electron measurements for both these events. Comparison of measured electron spectra and electron spectra for deriving electron characteristics from the X-ray measurements are described and discussed. We find. The electron spectra measured in the early stage of the localized morning maximum of X-ray emission strongly
Satellite spectra of heliumlike nickel
Hsuan, H.; Bitter, M.; Hill, K.W.; von Goeler, S.; Grek, B.; Johnson, D.; Johnson, L.C.; Sesnic, S.; Bhalla, C.P.; Karim, K.R.
Spectra of heliumlike nickel, Ni XXVII, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high-resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1s/sup 2/nl-1s2l'nl'' with n greater than or equal to 2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method.
Satellite spectra of heliumlike nickel
Hsuan, H.; Bitter, M.; Hill, K.W.; von Goeler, S. Grek, B.; Johnson, D.; Johnson, L.C.; Sesnic, S.; Bhalla, C.P.; Karim, K.R.
Spectra of heliumlike nickel, NiXXVII, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1s/sup 2/nl - 1s2l'nl'' with N greater than or equal to 2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method.
Mass spectra from field equations
NASA Astrophysics Data System (ADS)
Good, R. H., Jr.
A type of field quantization is developed which, in some cases, leads directly from a field equation to a mass spectrum. The starting point is a field-Hamiltonian setup of the field equations. A Schr�dinger-type wave function, a function of the field variables, is postulated and a Hamiltonian operator is inferred from the Hamiltonian function. A wave equation is suggested which has particle-type solutions only for special values of the rest mass. As examples, the spectra for the linear wave equation and for an equation with a sharply limited range of the field variable are discussed.
On the reality of red\\/blue-shifted narrow lines in X-ray spectra
P. Uttley
In recent years there have been many reported detections of highly redshifted or blueshifted narrow spectral lines (both emission or absorption) in the X-ray spectra of active galaxies, but these are all modest detections in terms of their statistical significance. If real, these represent a new and potentially powerful probe of the inner regions of AGN. In this talk we
Study on characteristic intrinsic fluorescence spectra of urine from ovarian cancer patients
NASA Astrophysics Data System (ADS)
Lu, Jun; Gao, Shumei; Yang, Youyi; Lu, Xiaohong; Chen, Guoqing
Ovarian cancer has the highest mortality rate among the gynecologic cancers, and it goes undetected because adequate technology does not exist to detect preinvasive or early stage disease. Fluorescence spectroscopy of urine may provide a cost-effective tool to improve precancer detection. This study describes initial investigation of the potential of intrinsic urine fluorescence spectra for detecting early ovarian cancer. Using the Xenon arc lamp to irradiate the urine from ovarian cancer, cervical carcinoma groups and healthy donors, we obtained fluorescence emission spectra. The three groups of samples show different emission spectra peak and fluorescence intensity. Ovarian cancer group has the largest displacement of maximum spectra peak at 380-400nm excitation wavelength. And the fluorescence intensity from ovarian cancer group is significantly higher with the healthy donors and cervical carcinoma group in comparison at the short wave excitation region of 320-360nm, while cervical carcinoma group has higher fluorescence intensity than ovarian cancer group at 380-500nm excitation. Characteristic fluorescence mechanism was studied through comparison of fluorescence spectra and software fitting image. Fluorescence spectra at 440nm excitation is found to be perfectly lorentzian fitted by three characteristic fluorescence peaks, which are originated form coproporphyrin, riboflavin and p-hydroxyphenol derivatives existing in the urine.
Collum, David B.
S31 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 10 #12;S32 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 11 #12;S33 1 H and 13 C NMR Spectra (see p S11) NH-i-Pr n-Bu NH-i-Pr n-Bu 12 Me Me 13 #12;S34 1 H and 13 C NMR Spectra (see p S11)NH-i-Pr Me Ph 14 #12;S35 1 H and 13 C NMR Spectra (see p S11
Hierarchical resolution of power spectra
NASA Astrophysics Data System (ADS)
Badii, R.; Finardi, M.; Broggi, G.; Sep�lveda, M. A.
We identify the basic ingredients determining the structure of the power spectra of non-linear dynamical systems in a hierarchical order of importance. The analysis, performed with the help of symbolic methods, shows that dynamical invariants such as topological and metric properties of the symbolic orbits explain the main qualitative features of the spectra, whereas the coordinate-dependent values of the observable itself represent a less relevant contribution. Consideration of simple dynamical models with increasing number of topological transition rules evidences the formation of coherent structures (peaks) and explains their position and size. By constructing the parse tree of the allowed symbolic itineraries, it is possible to estimate conditional probabilities by considering orbits belonging to adjacent tree levels. Accordingly, a Markov transition matrix is obtained for each level l and is used to generate signals with statistical properties which approximate those of the actual one increasingly better for l ? ?. A considerable improvement is achieved by recoding the original signal in terms of variable-length words and by re-applying the above procedure to the transformed signal, which is equivalent to a renormalization operation of the associated dynamical map. The accuracy of the estimates is directly related to the convergence of the scaling function for the conditional probabilities. Analytic results are presented for the simplest five Markov models arising from piecewise-linear, continuous, one-dimensional maps. Numerical studies have been performed for the logistic and H�non maps and for the Lorenz system.
Observation of ultralow-level Al impurities on a silicon surface by high-resolution grazing emission x-ray fluorescence excited by synchrotron radiation
Kubala-Kukus, A.; Banas, D.; Pajek, M. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Cao, W.; Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y.; Szlachetko, M. [Department of Physics, University of Fribourg, CH-1700 Fribourg (Switzerland); Salome, M.; Susini, J. [European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble (France); Szlachetko, J. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Department of Physics, University of Fribourg, CH-1700 Fribourg (Switzerland)
We demonstrate that ultralow-level Al impurities on a silicon surface can be measured by using the high-resolution grazing emission x-ray fluorescence (GEXRF) technique combined with synchrotron-radiation excitation. An Al-impurity level of about 10{sup 12} atoms/cm{sup 2} was reached by observing the Al K{alpha} x-ray fluorescence in the resonant Raman-scattering background-''free'' regime by choosing an appropriate beam energy below the Si K absorption edge. Present results show that by combining the GEXRF method with the vapor phase decomposition technique the 10{sup 7} atoms/cm{sup 2} level can be reached for Al detection on silicon. Finally, we found that the high-resolution GEXRF technique is a sensitive tool to study the morphology of surface nanostructures.
The EPIC-MOS Particle-Induced Background Spectra
NASA Technical Reports Server (NTRS)
Kuntz, K. D.; Sowden, S. L.
In order to analyse diffuse emission that fills the field of view, one must accurately characterize the instrumental backgrounds. For the XMM-Newton EPIC instrument these backgrounds include a temporally variable "quiescent" component. as well as the strongly variable soft proton contamination. We have characterized the spectral and spatial response of the EPIC detectors to these background components and have developed tools to remove these backgrounds from observations. The "quiescent" component was characterized using a combination of the filter-wheel-closed data and a database of unexposed-region data. The soft proton contamination was characterized by differencing images and spectra taken during flared and flare-free intervals. After application of our modeled backgrounds, the differences between independent observations of the same region of "blank sky" are consistent with the statistical uncertainties except when there is clear spectral evidence of solar wind charge exchange emission. Using a large sample of blank sky data, we show that strong magnetospheric SWCX emission requires elevated solar wind fluxes; observations through the densest part of the magnetosheath are not necessarily strongly contaminated with SWCX emission.
Radio Continuum Emission from FS CMa Stars
Rodriguez, L F; Miroshnichenko, A S
The FS CMa stars exhibit bright optical emission-line spectra and strong IR excesses. Very little is known of their radio characteristics. We analyzed archive Very Large Array data to search for radio continuum emission in a sample of them. There are good quality data for seven of the $\\sim$40 known FS CMa stars. Of these seven stars, five turn out to have associated radio emission. Two of these stars, CI Cam and MWC 300, have been previously reported in the literature as radio emitters. We present and briefly discuss the radio detection of the other three sources: FS CMa (the prototype of the class), AS 381, and MWC 922. The radio emission is most probably of a free-free nature but additional observations are required to better characterize it.
Helton, L. Andrew; Vacca, William D. [SOFIA Science Center, USRA, NASA Ames Research Center, M.S. N232-11, Moffett Field, CA 94035 (United States); Gehrz, Robert D.; Woodward, Charles E.; Shenoy, Dinesh P. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Wagner, R. Mark [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Evans, Aneurin [Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Krautter, Joachim [Landessternwarte-Zentrum fuer Astronomie der Universitaet, Koenigstuhl, D-69117 Heidelberg (Germany); Schwarz, Greg J. [American Astronomical Society, 2000 Florida Avenue, NW, Suite 400, Washington, DC 20009 (United States); Starrfield, Sumner, E-mail: firstname.lastname@example.com [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287 (United States)
We present Spitzer Space Telescope mid-infrared IRS spectra, supplemented by ground-based optical observations, of the classical novae V1974 Cyg, V382 Vel, and V1494 Aql more than 11, 8, and 4 years after outburst, respectively. The spectra are dominated by forbidden emission from neon and oxygen, though in some cases, there are weak signatures of magnesium, sulfur, and argon. We investigate the geometry and distribution of the late time ejecta by examination of the emission line profiles. Using nebular analysis in the low-density regime, we estimate lower limits on the abundances in these novae. In V1974 Cyg and V382 Vel, our observations confirm the abundance estimates presented by other authors and support the claims that these eruptions occurred on ONe white dwarfs (WDs). We report the first detection of neon emission in V1494 Aql and show that the system most likely contains a CO WD.
Skyglow effects in UV and visible spectra: radiative fluxes.
Kocifaj, Miroslav; Solano Lamphar, H A
Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment. PMID:23792881
Skyglow effects in UV and visible spectra: Radiative fluxes
NASA Astrophysics Data System (ADS)
Kocifaj, Miroslav; Solano Lamphar, Hector Antonio
Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment.
[Study on three-dimensional fluorescence spectra of phenanthrene].
Jin, Dan; Zhang, Yu-jun; Li, Guo-gang; Xiao, Xue; Wang, Zhi-gang; Yin, Gao-fang; Liu, Wen-qing
According to the high fluorescence quantum yields of polycyclic aromatic hydrocarbons (PAHs), the fluorescence spectra of phenanthrene were investigated by three dimensional fluorescence excitation-emission matrix (3DEEM). The results show that the three-dimensional fluorescence spectra of phenanthrene in aqueous solution mainly have two fluorescence peaks. On the basis of three-dimensional fluorescence spectrometry analysis of phenanthrene, the excitation wavelength of 255 nm and emission wavelength of 273 nm were chosen for the quantitative analysis of phenanthrene. The linear range for the determination of phenanthrene was 5.0-250.0 mg x mL(-1), its detection limit was 3. 88 ng x mL(-1), and its relative standard deviation was 4.23% (n=5). It was a good precision. It has been tested satisfactorily for the determination of artificial sample in tap water. The recoveries are in the range of 90%-105%. The method provided basis for the rapid monitoring of trace PAHs in water. PMID:19650480
Characterizing the infrared spectra of small, neutral, fully dehydrogenated PAHs
Mackie, C J; Bauschlicher, C W; Cami, J
We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2$\\mu$m, 5.5$\\mu$m and 10.6$\\mu$m; at longer wavelengths, there is a forest of emission features in the 16--30$\\mu$m range that appears as a structured continuum, but with a clear peak cent...
Ly$?$ Leaks in the Absorption Spectra of High Redshift QSOs
Jiren Liu; Hongguang Bi; Li-Zhi Fang
Spectra of high redshift QSOs show deep Gunn-Peterson absorptions on the blue sides of the \\Lya emissions lines. They can be decomposed into components called \\Lya leaks, defined to be emissive regions in complementary to otherwise zero-fluxed absorption gaps. Just like \\Lya absorption forests at low redshifts, \\Lya leaks are both easy to find in observations and containing rich sets of statistical properties that can be used to study the early evolution of the IGM. Among all properties of a leak profile, we investigate its equivalent width in this paper, since it is weakly affected by instrumental resolution and noise. Using 10 Keck QSO spectra at $z\\sim6$, we have measured the number density distribution function $n(W,z)$, defined to be the number of leaks per equivalent width $W$ and per redshift $z$, in the redshift range $5.4 - 6.0$. These new observational statistics, in both the differential and cumulative forms, fit well to hydro numerical simulations of uniform ionizing background in the $\\Lambda$CDM cosmology. In this model, Ly $\\alpha$ leaks are mainly due to low density voids. It supports the early studies that the IGM at $z\\simeq6$ would still be in a highly ionized state with neutral hydrogen fraction $\\simeq 10^{-4}$. Measurements of $n(W,z)$ at $z>6$ would be effective to probe the reionization of the IGM.
Utilizing Thermal Infrared Spectra of Mars for Mission Planning
NASA Astrophysics Data System (ADS)
Kirkland, L. E.; Forney, P. B.; Herr, K. C.; Keim, E. R.
Reflectance and emission spectroscopy remain the most capable method for mineral identification from orbit. However, to best utilize spectra returned from Mars for mission planning, the current level of understanding of the spectral signature of weathered and rough materials should be considered. Materials measured in the laboratory tend to have band strengths that are stronger than those measured in the field. This difference results mainly from surface roughness, weathering effects, and the presence of a mixture of different materials in the field of view (mixed pixel effect). Thus it is critical to extend spectral measurements from the laboratory into the field in order to understand the spectral behavior of real-world materials. This is best done by utilizing a combination of airborne, field, and laboratory spectra of terrestrial materials, and then applying the lessons learned to spectra recorded of Mars. The ability of any spectral instrument to detect and identify minerals depends on a combination of (1) the mineral's band strength; (2) band width; (3) the instrument's spectral resolution; (4) signal-to-noise ratio (SNR); and (5) atmospheric interference. These points are not always considered in quotes of the detection limits for a given instrument and material. Here we discuss these effects, and explain their relevance for assessing the order in which spectral instruments should be flown to best implement a phased approach to "follow the water," and for landing site selection and sample return.
Multivariate calibration applied to the quantitative analysis of infrared spectra
Haaland, D.M.
Multivariate calibration methods are very useful for improving the precision, accuracy, and reliability of quantitative spectral analyses. Spectroscopists can more effectively use these sophisticated statistical tools if they have a qualitative understanding of the techniques involved. A qualitative picture of the factor analysis multivariate calibration methods of partial least squares (PLS) and principal component regression (PCR) is presented using infrared calibrations based upon spectra of phosphosilicate glass thin films on silicon wafers. Comparisons of the relative prediction abilities of four different multivariate calibration methods are given based on Monte Carlo simulations of spectral calibration and prediction data. The success of multivariate spectral calibrations is demonstrated for several quantitative infrared studies. The infrared absorption and emission spectra of thin-film dielectrics used in the manufacture of microelectronic devices demonstrate rapid, nondestructive at-line and in-situ analyses using PLS calibrations. Finally, the application of multivariate spectral calibrations to reagentless analysis of blood is presented. We have found that the determination of glucose in whole blood taken from diabetics can be precisely monitored from the PLS calibration of either mind- or near-infrared spectra of the blood. Progress toward the non-invasive determination of glucose levels in diabetics is an ultimate goal of this research. 13 refs., 4 figs.
Modeling of Neutron Spectra Based on Activation Analysis
NASA Astrophysics Data System (ADS)
Jovancevic, N.; Fridman, M.; Daraban, L.; Hambsch, F.-J.; Oberstedt, S.; Hult, M.; Lutter, G.; Marissens, G.; Stroh, H.
Safe and economical use of nuclear energy and particularly the development of GEN-IV reactors impose a better understanding of prompt neutron emission in fission, as well as of the fission process as such. Therefore, accurate measurements of the prompt fission neutron spectra (PFNS) are very important. In this work, we are testing the possibility to determine the PFNS by an activation method called DONA (DOsimetry and Spectroscopy using Neuron Activation) recently developed at IRMM (Wieslander et al., 2010, L�vestam et al., 2009). This type of modeling of the neutron spectra, based on the activation analysis, can provide new information about an old problem which still exists today, i.e. the discrepancy between measured integral and differential data (Capote et al., 2012). The problem is that the calculated average cross section for a certain neutron reaction, by using the differential experimental PFNS, in many cases cannot reproduce satisfactorily the integral measured cross section values. The modeling of the neutron spectra by the DONA technique was tested with the standard neutron spectrum of the spontaneous fission of 252Cf. We analyzed the sensitivity of the unfolding procedure to the initial neutron energy spectrum, the influence of the neutron scattering, the possibility of using different activation reactions and we also made an estimation of the lowest measurable neutron fluence rate.
Disk-averaged Spectra & light-curves of Earth
G. Tinetti; V. S. Meadows; D. Crisp; W. Fong; N. Kiang; E. Fishbein; T. Velusamy; E. Bosc; M. Turnbull
We are using computer models to explore the observational sensitivity to changes in atmospheric and surface properties, and the detectability of biosignatures, in the globally averaged spectra and light-curves of the Earth. Using AIRS (Atmospheric Infrared Sounder) data, as input for atmospheric and surface properties, we have generated spatially resolved high-resolution synthetic spectra using the SMART radiative transfer model, for a variety of conditions, from the UV to the far-IR (beyond the range of current Earth-based satellite data). We have then averaged over the visible disk for a number of different viewing geometries to quantify the sensitivity to surface types and atmospheric features as a function of viewing geometry, and spatial and spectral resolution. These results have been processed with an instrument simulator to improve our understanding of the detectable characteristics of Earth-like planets as viewed by the first generation extrasolar terrestrial planet detection and characterization missions (Terrestrial Planet Finder/Darwin and Life finder). The wavelength range of our results are modelled over are applicable to both the proposed visible coronograph and mid-infrared interferometer TPF architectures. We have validated this model against disk-averaged observations by the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES). This model was also used to analyze Earth-shine data for detectability of planetary characteristics and biosignatures in disk-averaged spectra.
Reflectance spectra of primitive chondrites
NASA Astrophysics Data System (ADS)
Trigo-Rodr�guez, J. M.; Moyano-Cambero, C. E.; Llorca, J.
We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 ?m electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.
Near infrared spectra of the Orion bar
NASA Astrophysics Data System (ADS)
Marconi, A.; Testi, L.; Natta, A.; Walmsley, C. M.
We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2. From our molecular hydrogen data, we conclude that densities are moderate (3-6x 10(4) cm(-3) ) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~ 10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317mum OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x 10(4) greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10(4) \\percc. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres.
OH spectroscopy and chemistry investigated with astronomical sky spectra
NASA Astrophysics Data System (ADS)
Cosby, P. C.; Slanger, T. G.
This study summarizes the use of a large catalog of astronomical sky spectra to study different aspects of OH spectroscopy and chemistry in the terrestrial night sky. The sky spectra are unique in that they have high spectral resolution, cover the entire visible wavelength region in one exposure, and are intensity-calibrated with respect to standard stars. The intensity calibration, in particular, allows a significant revision to the OH Meinel band intensity distribution that has been in use for 43 years and permits critical evaluation of the many available sets of OH emission coefficients. The spectra further allow the OH rovibrational population distributions to be monitored throughout many nights. The OH vibrational population distribution is found to change during the night, with the population ratio between the extreme high-v and low-v levels that we can detect, v = 9 and v = 3, varying by as much as a factor of two; the low-v levels being predominant earlier in the night. It has been common to determine the kinetic temperature of the OH emission region by assuming that it is equal to the low-J rotational temperature associated with particular OH bands, typically bands originating in the v = 6 and v = 8 levels. The present calibrated data set reveals that the rotational temperatures are significantly greater for high-v than for low-v levels, the typical difference between v = 3 and v = 8 being 15 K. Previous attempts to establish that a difference existed are consistent with our current observations, although conclusions from those earlier results were limited by relatively wide error limits. The present rovibrational population measurements, which extend to high rotational levels (J' <= 25.5), also reveal that the high-J populations are largely independent of vibrational level - the high-J population in v = 3 is similar to that in v = 7.
Thermal emission in the ultrastrong coupling regime
A. Ridolfo; M. Leib; S. Savasta; M. J. Hartmann
We study thermal emission of a cavity quantum electrodynamic system in the ultrastrong-coupling regime where the atom-cavity coupling rate becomes comparable the cavity resonance frequency. In this regime, the standard descriptions of photodetection and dissipation fail. Following an approach that was recently put forward by Ridolfo et al.[arXiv:1206.0944], we are able to calculate the emission of systems with arbitrary strength of light matter interaction, by expressing the electric field operator in the cavity-emitter dressed basis. Here we present thermal photoluminescence spectra, calculated for given temperatures and for different couplings in particular for available circuit QED parameters.
Measurement of muonium emission from silica aerogel
Bakule, P; Contreras, D; Esashi, M; Fujiwara, Y; Fukao, Y; Hirota, S; Iinuma, H; Ishida, K; Iwasaki, M; Kakurai, T; Kanda, S; Kawai, H; Kawamura, N; Marshall, G M; Masuda, H; Matsuda, Y; Mibe, T; Miyake, Y; Okada, S; Olchanski, K; Olin, A; Onishi, H; Saito, N; Shimomura, K; Strasser, P; Tabata, M; Tomono, D; Ueno, K; Yokoyama, K; Yoshida, S
Emission of muonium ($\\mu^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.
Ruffini, R.; Siutsou, I. A.; Vereshchagin, G. V. [ICRANet, 65122, p.le della Repubblica, 10, I-65122 Pescara (Italy)
We derive the optical depth and photospheric radius of relativistic outflows using a model of a relativistic wind with a finite duration. We also discuss the role of radiative diffusion in such an outflow. We numerically solve the radiative transfer equation and obtain light curves and observed spectra of the photospheric emission. The spectra we obtain are nonthermal and in some cases have Band shapes.
On the Viability of the PAH Model as an Explanation of the Unidentified Infrared Emission Features
NASA Astrophysics Data System (ADS)
Zhang, Yong; Kwok, Sun
Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper, we report the results of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal, and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggests that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.
On the viability of the PAH model as an explanation of the unidentified infrared emission features
Zhang, Yong
Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.
Prompt fission neutron spectra of n+235U above the (n,nf) fission threshold
NASA Astrophysics Data System (ADS)
Shu, Neng-Chuan; Jia, Min; Chen, Yong-Jing; Liu, Ting-Jin
Calculations of prompt fission neutron spectra (PFNS) from the 235U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n,xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n,xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n,nf) or (n,2nf) reactions influences the PFNS shape, and the neutron spectra of the (n,xnf) fission-channel are soft compared with the neutron spectra of the (n,f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case. Supported by National Natural Science Foundation of China (11205246, 91126010, U1230127, 91226102), IAEA CRP (15905), and Defense Industrial Technology Development Program (B0120110034)
FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
M. C. Cushing; J. T. Rayner; S. P. Davis; W. D. Vacca
We present medium-resolution z-, J-, and H-band spectra of four late-type dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine the origin of numerous weak absorption features throughout their near-infrared spectra, and motivated by the recent tentative identification of the E 4\\Pi- A ^4\\Pi system of FeH near 1.6 microns in umbral and cool star spectra, we have compared the dwarf spectra to a laboratory FeH emission spectrum. We have identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra of the dwarfs. In particular, we have identified 34 features which dominate the appearance of the H-band spectra of the dwarfs and which appear in the laboratory FeH spectrum. Finally, all of the features are either weaker or absent in the spectrum of the L7.5 dwarf which is consistent with the weakening of the known FeH bandheads in the spectra of the latest L dwarfs.
FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
Cushing, M C; Davis, S P; Vacca, W D
We present medium-resolution z-, J-, and H-band spectra of four late-type dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine the origin of numerous weak absorption features throughout their near-infrared spectra, and motivated by the recent tentative identification of the E 4\\Pi- A ^4\\Pi system of FeH near 1.6 microns in umbral and cool star spectra, we have compared the dwarf spectra to a laboratory FeH emission spectrum. We have identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra of the dwarfs. In particular, we have identified 34 features which dominate the appearance of the H-band spectra of the dwarfs and which appear in the laboratory FeH spectrum. Finally, all of the features are either weaker or absent in the spectrum of the L7.5 dwarf which is consistent with the weakening of the known FeH bandheads in the spectra of the latest L dwarfs.
Optical spectra and Judd-Ofelt analysis of Pr3+ and Er3+ in different phosphate glasses
NASA Astrophysics Data System (ADS)
Seshadri, M.; Venkata Rao, K.; Hemantha Kumar, G. N.; Ratnakaram, Y. C.
Optical absorption and emission spectra of Pr3+ and Er3+ ions in different (Li, Na, K, Ca, LiNa, LiK and NaK) phosphate glasses are presented. Judd-Ofelt analysis has been carried out for the absorption spectra and studied variation of Judd-Ofelt intensity parameters (??, ?=2, 4, 6) with the variation of glass matrix. From the variation of peak wavelengths of the hypersensitive transition and ?2 parameter structural details are obtained for both Pr3+ and Er3+ ions in these glass matrices. Radiative transition rates (AT), radiative lifetimes (?xR), branching ratios (?R) and integrated absorption cross-sections (?) for certain excited states of Pr3+ and Er3+ ions are obtained. The stimulated emission cross-sections (?P) have been determined from the line shape of the emission spectra of Pr3+ and Er3+ in these phosphate glass matrices.
Infrared spectra of natural and synthetic malachites
NASA Astrophysics Data System (ADS)
Schuiskii, A. V.; Zorina, M. L.
IR absorption and reflection spectra of dark and light samples of natural and synthetic malachite over 400-4000 cm-1 are studied for the purpose of improving the synthesis technique and in order to distinguish between natural malachite and malachite grown from ammonia solutions. Nitrogen was not detected in the IR spectra or in microprobe analyses of the synthetic material. The differences found in the IR spectra were insignificant and cannot be regarded as distinctive indicators of these materials.
Vibrational spectra and structure of dimethylaminodichlorophosphine.
NASA Technical Reports Server (NTRS)
Durig, J. R.; Casper, J. M.
Evaluation of the infrared spectra of dimethylaminodichlorophosphine and dimethylaminodichlorophosphine-d sub 6 recorded from 4000 to 33 per cm in the gas and solid phases. The Raman spectra of the liquid and solid phases for both compounds were also recorded. The spectra were consistent with the presence of only one isomer over the range of phases and temperatures studied. Available experimental data were discussed in connection with the spectra, and it is concluded that the molecule exists in the gauche conformer with the PNC2 portion of the molecule planar. A vibrational assignment is proposed for the molecule.
Infrared spectra of thyroid tumor tissues
NASA Astrophysics Data System (ADS)
Tolstorozhev, G. B.; Skornyakov, I. V.; Butra, V. A.
We used infrared spectroscopy methods to study thyroid tumor tissues removed during surgery. The IR spectra of the surgical material are compared with data from histological examination. We show that in malignant neoplasms, the spectra of proteins in the region of C=O vibrations are different from the spectra of these substances in benign tumors and in tissues outside the pathological focus at a distance >1 cm from the margin of the tumor. The differences in the spectra are due to changes in the supermolecular structure of the proteins, resulting from rearrangement of the system of hydrogen bonds. We identify the spectral signs of malignant pathologies.
Triplet excition emissions of octafluoronaphthalene crystalline complexes with naphthalene and durene
NASA Astrophysics Data System (ADS)
Chen, Freeman P.; Prasad, Paras N.
The phosphorescence spectra of naphthalene-octafluoronaphthalene and durene-octafluoronaphthalene at 4.2 K reveal a localized exciton emission from octafluoronaphthalene, a weak intercomponent triplet-states quasi-resonance and a weak exciton-phonon coupling.