Investigation of electronic structure of ternary molybdenum sulphides by means of x-ray emission and photoelectron spectroscopy

The electronic structure of superconducting Chevrel phases (SnMo₆S₈, PbMo₆S₈, Cu_2.8Mo₆S₈) and nonsuperconducting spinel (GaMo₄S₈) was investigated by X-ray emission (XES) and X-ray photoelectron (XPS) spectroscopy. The comparison of the obtained results with band structure and cluster calculations of given compounds was performed.     

Investigation of the band structure of germanium chalcogenides by means of photoelectron spectroscopy

The valence band photoelectron spectra of amorphous GeS, GeSe and GeTe have been measured. The ultraviolet and X-ray excited spectra show three bands associated with bonding p-states, anti-bonding and bonding s-states, respectively. In the ultraviolet photoemission spectra the p-band shows a pronounced fine structure. Features of the valence band density of states estimated on the basis of a tightbinding model are in reasonable agreement with experiment. Some problems connected with the extension of the ionicity concept of Phillips and van Vechten to the IV–VI compounds are discussed.     

Investigation of the electronic structure of the Fe-Si systems by x-ray photoelectron spectroscopy

The paper reports the results of investigations of the valence bands for the Fe-Si alloys containing 50 and 25 at. % Si and the alloys at a metalloid content of 2–20 at. %. The x-ray photoelectron spectra of the valence bands are compared with the band calculations of the total and partial densities of states for the stoichiometric alloys by the tight-binding linearized muffin-tin orbital method.     

Investigation of TiC-C coatings by X-ray photoelectron spectroscopy

Titanium carbide-based coatings deposited by arc-technology in C₂H₂/Ar atmosphere were studied by X-ray photoelectron spectroscopy. It was found that, in addition to the cubic phase of TiC _x O _y oxycarbide, the films contain carbon in the amorphous, presumably graphite-like state. In carbon C1s spectra, bands at 282.0, 284.4, and 286.0 eV correspond to the TiC _x state, amorphous carbon, and C-C bonds, respectively. The maximum at 283.0 eV was interpreted as the C state in titanium carbide nanoforms, i.e., Ti₁₄C₁₃ clusters or Ti₈C₁₄ carbohedra. The phase ratio was varied by coating deposition conditions, i.e., TiC/a-C deposition by Ti cathode sputtering in C₂H₂/Ar, and composite Ti/C target sputtering in Ar and C₂H₂/Ar. When using the Ti cathode and C₂H₂/Ar gas mixture, the ratio of carbide and amorphous a-C phases was estimated as 1: 1; the surface layer ～15 nm thick was enriched with amorphous carbon. It was assumed that TiC/a-C composite coatings with an additional a-C film on the surface would have an increased stability in reaction media and good biocompatibility.     

Investigation of the initial stages of oxidation of microcrystalline silicon by means of X-ray photoelectron spectroscopy

XPS Si2p spectra of microcrystalline silicon (μc-Si), prepared by plasma chemical transport are reported and the initial stages of oxidation are studied: In comparison with single crystal Si(111) surfaces, μc-Si samples are remarkable resistant to surface oxidation. A short exposure to air results in negligible oxygen adsorption (intensity ratio of 01s to Si2p peaks is less than 0.018 after more than3 × 10¹¹ Langmuirs exposure to air). Intensive oxidation treatment is required to produce an oxide layer and evidence supporting a preferential grain boundary oxidation mechanism is presented. The surface plasmon structure observed in the Si2p spectrum provides complementary information on the remarkably low oxidation rate of the crystallite surfaces as compared to the grain boundaries.     

Electronic structure of carbyne studied by X-ray photoelectron spectroscopy and X-ray emission spectroscopy

The electronic structure of amorphous carbyne has been investigated by X-ray photoelectron spectroscopy and X-ray emission spectroscopy. Carbyne band structure has been calculated semiempirically and the experimental data have been interpreted on the basis of the calculation results. The valence band width was found to be about 20 eV which is the same as that in all other condensed carbon structures. The fine satellite structure near the 1s line of carbon has been studied. It is shown that the energy bands in carbyne are arranged in a mirror-like way relative to the Fermi level. The real carbyne structure is susceptible to conformations which affect primarily the π-subband structure.     

Investigation by X-ray photoelectron spectroscopy of the transient oxidation of NiAl

X-ray photoelectron spectroscopy (XPS) has been used to study the oxidation of NiAl in oxygen at atmospheric pressure. Prior to oxidation, the native oxide scale on the specimen was removed by ion sputtering and the specimens were (pre-)heated in vacuum before exposure to oxygen. At low oxidation temperatures (<750 K) scales consisted of Al₂O₃ and NiAl₂O₄, with a thin surface layer of NiO, but at higher temperatures were of Al₂O₃, apart from about 0.5 at % Ni. The Ni content in the latter case was constant throughout the scale and did not increase dramatically near the alloy/oxide interface. In the experimental conditions used in this study, initial formation of NiO and NiAl₂O₄ seems to be avoided at the higher oxidation temperatures ( > 750 K).     

Electronic structure of black phosphorus studied by X-ray photoelectron spectroscopy

The X-ray photoelectron spectrum of black phosphorus has been measured for the first time. The features in the valence band spectrum are found to be in good agreement with those of the valence state density recently calculated on the basis of a pseudopotential method. The 2s and 2p core spectrum of black phosphorus is also discussed.     

Investigation of platinum oxide-titanium films by the method of X-ray photoelectron spectroscopy

Platinum oxide-titanium films that are produced by thermolysis of H₂PtCl₆ in the presence of NO ₃ ⁻ on a titanium surface are investigated by the method of x-ray photoelectron spectroscopy. It is shown that making nitrates a part of the composition leads to an increase in the content of oxidized forms of platinum and the appearance of titanium in the film. Belarusian State Technological University, 13a, Sverdlov St., Minsk, 220630, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 536–538, July–August, 1997.     

X射线光电子能谱

X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）技术也被称作用于化学分析的电子能谱（electron spectroscopy for chemical analysis,ESCA）.XPS属表面分析法,它可以给出固体样品表面所含的元素种类、化学组成以及有关的电子结构重要信息,在各种固体材料的基础研究和实际应用中起着重要的作用.文章简要介绍了XPS仪器的工作原理和分析方法,并给出了XPS在科学研究工作中的应用实例.     

X射线光电子能谱

X射线光电子能谱（X-ray photoelectron spectroscopy，XPS）技术也被称作用于化学分析的电子能谱（electron spectroscopy for chemical analysis，ESCA）．XPS属表面分析法，它可以给出固体样品表面所含的元素种类、化学组成以及有关的电子结构重要信息，在各种固体材料的基础研究和实际应用中起着重要的作用．文章简要介绍了XPS仪器的工作原理和分析方法，并给出了XPS在科学研究工作中的应用实例．     

X-ray photoelectron spectroscopy and calculation of the electronic structure in iron based alloys under phase transformation

An experimental method which allows us to survey alterations in the X-ray photoelectron spectra under

- to

- transition is suggested. The densities of states of valence electrons calculated in the multi-band coherent potential approximation (CPA) reflect general features of XPS measurements. Our calculations have allowed us to determine contributions from electrons which occupy e_g- and t_2g- orbitals, oriented along different directions in crystal lattice to the cohesive energy.     

Surface segregation in yttria-stabilized zirconia by means of angle resolved X-ray photoelectron spectroscopy

Surface segregation of cations in undoped and titanium-doped yttria-stabilized zirconia was studied in air in the temperature range from 800 to 1400°C. Surface composition and distribution of the elements across the surface layer was examined using angle resolved X-ray photoelectron spectroscopy. The annealing procedure induced a silicon-rich surface layer of low zirconium concentration. The yttrium concentration only slightly increased at the surface. Enrichment factor of titanium in the titanium-doped yttria-stabilized zirconia was found to be higher than that of yttrium. No significant correlation between segregation of other cations was found.     

Investigation of electronic structure of Nd-doped TiO2 nanoparticles using synchrotron radiation photoelectron spectroscopy

Doping with transition metal ions in TiO₂ has been found effective to modify the electronic structure of TiO₂ nanoparticles. Application of synchrotron radiation photoelectron spectroscopy (SRPES) to Nd-doped TiO₂ nanoparticles revealed that there existed different peak positions and structure with different doping concentration in the valence band spectra. From the onset of valence band spectrum, it was observed that doping Nd ions alters the electronic structure and makes the band gap of TiO₂ narrow.     

Synthesis of platinum metalloporphyrins and investigation of their electronic structure by photoelectron spectroscopy

Features of the electronic structure of the valence band and Pt4f, Pt4d, C1s, O1s, and N1s core levels of the tetraphenylporphyrin (TPP) and synthesized Pt-TPP(p-COOCH₃)₄, Pt-TPP(m-OCH₃)₄, and PtCl₂-TPP(m-OCH₃)₄ platinum metalloporphyrins are investigated by photoelectron spectroscopy.     

Deconvolution in X-ray photoelectron spectroscopy

Published Mg and Al Kα X-ray lineshapes have been used to study the removal of the effects of X-ray broadening in XPS spectra by deconvolution. These results are compared with spectra obtained for the same specimens in the same instrument using a monochromatic X-ray source. The use of deconvolution to remove analyzer broadening from spectra has also been examined, and it has been verified experimentally that the maximum improvement in the full width at half-maximum of a peak that can be achieved is 30%. Deconvolution has also been examined as a means to remove backgrounds from XPS spectra over wide energy ranges, up to 100 eV.     

Investigation of self-organizing thiol films by optical second harmonic generation and X-ray photoelectron spectroscopy

The adsorption of self-organizing thiol films on polycrystalline gold substrates was investigated in situ by optical second harmonic generation. Growth of the films could be detected at submonolayer coverage. For a comparison with classical surface analytical methods the thiol coverage was measured ex situ by X-ray photoelectron spectroscopy. We find that formation of ordered thiol films up to monolayer coverage can be described by Langmuir adsorption kinetics.