{'fraction_non_alphanumeric': 0.05391073795846222, 'fraction_numerical': 0.035793194874060984, 'mean_word_length': 4.6725146198830405, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Surface Studies of Thiolate Adsorbates on Some Metals

7 Abstract The results and discussions in this thesis are based on my studies about selfassembled thiol layers on gold, platinum, silver and copper surfaces. These kinds of layers are two-dimensional, one molecule thick and covalently organized at the surface. They are an easy way to modify surface properties. Self-assembly is today an intensive research field because of the promise it holds for producing new technology at nanoscale, the scale of atoms and molecules. These kinds of films have applications for example, in the fields of physics, biology, engineering, chemistry and computer science. Compared to the extensive literature concerning self-assembled monolayers (SAMs) on gold, little is known about the structure and properties of thiolbased SAMs on other metals. In this thesis I have focused on thiol layers on gold, platinum, silver and copper substrates. These studies can be regarded as a basic study of SAMs. Nevertheless, an understanding of the physical and chemical nature of SAMs allows the correlation between atomic structure and macroscopic properties. The results can be used as a starting point for many practical applications. X-ray photoelectron spectroscopy (XPS) and synchrotron radiation excited high resolution photoelectron spectroscopy (HR-XPS) together with time-offlight secondary ion mass spectrometry (ToF-SIMS) were applied to investigate thin organic films formed by the spontaneous adsorption of molecules on metal surfaces. Photoelectron spectroscopy was the main method used in these studies. In photoelectron spectroscopy, the sample is irradiated with photons and emitted photoelectrons are energy-analyzed. The obtained spectra give information about the atomic composition of the surface and about the chemical state of the detected elements. It is widely used in the study of thin layers and is a very powerful tool for this purpose. Some XPS results were complemented with ToF-SIMS measurements. It provides information on the chemical composition and molecular structure of the samples. Thiol (1-Dodecanethiol, CH3(CH2)11SH) solution was used to create SAMs on metal substrates. Uniform layers were formed on most of the studied metal surfaces. On platinum, surface aligned molecules were also detected in investigations by XPS and ToF-SIMS. The influence of radiation on the layer structure was studied, leading to the conclusion that parts of the hydrocarbon chains break off due to radiation and the rest of the layer is deformed. The results obtained showed differences depending on the substrate material. The influence of oxygen on layer formation was also studied. Thiol molecules were found to replace some of the oxygen from the metal surfaces. List of Publications 8 List of publications The content of this thesis is based on the following published papers. The author was also responsible for performing all the XPS measurements and most of the sample preparations. The papers are referred to by their Roman numerals in the text. I T. Laiho, J.A. Leiro and J. Lukkari: XPS study of irradiation damage and different metal-sulfur bonds in dodecanethiol monolayers on gold and platinum surfaces. Applied Surface Science 2003, 212-213, 525-529. II T. Laiho, J.A. Leiro, S. Mattila, M. Heinonen and J. Lukkari: Photoelectron spectroscopy study of irradiation damage and metalsulfur bonds of thiol on silver and copper surfaces. Journal of Electron Spectroscopy and Related Phenomena 2005, 142, 105-112. III T. Laiho, J. Lukkari, M. Meretoja, K. Laajalehto, J. Kankare and J.A. Leiro: Chemisorption of alkyl thiols and S-alkyl thiosulfates on Pt(111) and polycrystalline platinum surfaces. Surface Science 2005, 584, 83–89. IV T. Laiho and J.A. Leiro: Influence of initial oxygen on the formation of thiol layers. Applied Surface Science 2006, 252, 6304–6312. V T. Laiho and J.A. Leiro: ToF-SIMS study of 1-dodecanethiol adsorption on Au, Ag, Cu and Pt surfaces. Surface and Interface Analysis 2008, 40, 51-59. List of Publications 9 A list of other published articles, concerning XPS studies of sulfur-containing species and of thin organic layers, where I am a co-author. These publications are related to this work, but were not included in the thesis. K. Laajalehto, I. Kartio, T. Kaurila, T. Laiho and E. Suoninen: Investigation of copper sulfide surfaces using synchrotron radiation excited photoemission spectroscopy, Mathieu, H.J., Reihl, B. and Briggs, D. (Ed.), Proc. of 6th European Conference on Applications of Surface and Interface Analysis (ECASIA 95), pp. 717-720, John Wiley & Sons, Chichester, England (1996). I. Kartio, G. Wittstock, K. Laajalehto, D. Hirsch, J. Simola, T. Laiho, R. Szargan and E. Suoninen: Detection of elemental sulfur on galena oxidized in acidic solution. International Journal of Mineral Processing 1997, 51, 293-301. K. Laajalehto, J. Leppinen, I. Kartio and T. Laiho: XPS and FTIR study of the influence of electrode potential on activation of pyrite by copper or lead. Colloids and Surfaces A 1999, 154, 193-199. K. Laajalehto, I. Kartio, M. Heinonen and T. Laiho: Temperature controlled photoelectron spectroscopic investigation of volatile species on PbS (100) surface. Japanese Journal of Applied Physics 1999, 38-1, 265-268. J. Lukkari, M. Salomaki, T. Aaritalo, K. Loikas, T. Laiho and J. Kankare: Preparation of multilayers containing conjugated thiophene-based polyelectrolytes. Layer-by-layer assembly and viscoelastic properties. Langmuir 2002, 18(22), 8496-8502. J.A. Leiro, M.H. Heinonen, T. Laiho and I.G. Batirev: Core-level XPS spectra of fullerene, highly oriented pyrolitic graphite, and glassy carbon. Journal of Electron Spectroscopy and Related Phenomena 2003, 128(23), 205-213. A. Viinikanoja, J. Lukkari, T. Aaritalo, T. Laiho and J. Kankare: Phosphonic acid derivatized polythiophene: a building block for metal phosphonate and polyelectrolyte multilayers. Langmuir 2003, 19(7), 2768-2775. List of Publications 10 J.P. Matinlinna, K. Laajalehto, T. Laiho, I. Kangasniemi, L.V.J. Lassila and P.K. Vallittu: Surface analysis of Co-Cr-Mo-alloy and Ti substrates silanized with trialkoxysilanes and silane mixtures. Surface and Interface Analysis 2004, 36(3), 246-253. M. Salomaki, T. Laiho and J. Kankare: Counteranion-controlled properties of polyelectrolyte multilayers. Macromolecules 2004, 37(25), 9585-9590. H. Paloniemi, T. Aaritalo, T. Laiho, H. Liuke, N. Kocharova, K. Haapakka, F. Terzi, R. Seeber, J. Lukkari: Water-soluble full-length single-wall carbon nanotube polyelectrolytes: preparation and characterization. Journal of Physical Chemistry B 2005, 109(18), 8634-8642. S. Mattila, J.A. Leiro, M. Heinonen and T. Laiho: Core level spectroscopy of MoS2. Surface Science 2006, 600(24), 5168-5175.