共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Yu. Usachev A. M. Shikin A. Yu. Varykhalov V. K. Adamchuk O. Rader 《Physics of the Solid State》2007,49(5):949-957
The formation of angle-resolved photoelectron spectra for crystal surfaces with a complex geometric relief is considered. A simple model of a thin corrugated single-crystal film is proposed which illustrates the main specific features of this process. It is shown that photoelectron spectra of these surfaces exhibit features that, rather than reflecting the true electronic structure of the system, result from its superposition with the geometric structure. The validity of the model is demonstrated with the use of a physical system based on Ni(771) and Ni(755) stepped surfaces with periodic steps. It is revealed that, as a graphite coating grows to a monolayer thickness, these surfaces become faceted to form a geometrically nonuniform surface relief. The photoelectron spectra obtained for such a surface can be used to derive a quantitative characteristic of both the electronic structure of the surface and its geometric properties. The surface topography of the system is determined independently using scanning tunneling microscopy. 相似文献
2.
This paper discusses fluorination of biomedical-grade yttria-stabilized zirconia (YSZ) by sulfur hexafluoride plasma treatment and characterization of near-surface chemistry products by X-ray photoelectron spectroscopy (XPS). Deconvolution of the Zr 3d and Y 3d XPS core level spectra revealed formation of both ZrF4 and YF3. In addition, seven-coordinate ZrO2F5 and/or ZrO3F4 phases were deconvolved, retaining similar atomic coordination as the parent oxide and believed to have formed by substitutional displacement of oxygen by fluorine. No additional components attributed to yttria oxyfluoride were deconvolved. Argon ion sputter depth profiling determined the overlayer to be ∼4.0 nm in thickness, and angle resolved XPS showed no angle dependence on component percentages likely due to fluorination extending into the grain boundaries of the polycrystalline substrates. Importantly, the conversion layer did not induce any apparent change in zirconia crystallinity by inspection of Zr-O 3d5/2,3/2 peak positions and full-width-at-half-maximum values, important for retaining its desirable mechanical properties. 相似文献
3.
R.I. Hegde S.R. Sainkar S. Badrinarayanan A.P.B. Sinha 《Journal of Electron Spectroscopy and Related Phenomena》1981,24(1):19-25
X-ray photoelectron spectra of Pb98Sn2, Ag95Sn5, Sb95Sn5 and Cd99.6Sn0.4 have been recorded using a VG Scientific ESCA-3 Mk. II electron spectrometer. In all cases the Sn 3d level in the alloys is compared with the 3d level in pure tin. The binding energy shifts are explained on the basis of electronegativity and near-neighbour interactions. It is found that increased coordination number as well as increased electronegativity of the neighbouring atoms increases the binding energy of the core electron level. 相似文献
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Study of nanocrystalline V02 thin films prepared by magnetron sputtering and post-oxidation 下载免费PDF全文
Nanocrystalline VO2 thin films were deposited onto glass slides by direct current magnetron sputtering and postoxidation. These films undergo semiconductor-metal transition at 70 ℃, accompanied by a resistance drop of two magnitude orders. The crystal structures and surface morphologies of the VO2 films were characterized by x-ray diffraction (XRD) and atomic force microscope (AFM), respectively. Results reveal that the average grain size of VO2 nanograins measured by XRD is smaller than those measured by AFM. In addition, Raman characterization indicates that stoichiometric VO2 and oxygen-rich VO2 phases coexist in the films, which is supported by x-ray photoelectron spectroscopy (XPS) results. Finally, the optical properties of the VO2 films in UV-visible range were also evaluated. The optical band gap corresponding to 2p-3d inter-band transition was deduced according to the transmission and reflection spectra. And the deduced value, Eopt2p-3d : 1.81 eV, is in good agreement with that previously obtained by theoretical calculation. 相似文献
5.
L.S. Kibis A.I. Titkov A.I. Stadnichenko S.V. Koscheev A.I. Boronin 《Applied Surface Science》2009,255(22):9248-9254
The low-temperature oxidation of polycrystalline palladium by RF oxygen plasma was studied via X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Detailed information about the electronic states of palladium and oxygen was obtained based on the XPS curve fitting analysis of Pd3d and Pd3p + O1s lines. The results showed that Pd oxidation by oxygen plasma was different from Pd oxidation in pure O2 at high temperature. SEM shows well-structured submicron PdO particles result from oxidation in pure O2, whereas plasma oxidation results in the predominant formation of two-dimensional PdO structures covering the initial crystallites of the Pd foil. Further oxidation to a three-dimensional PdO phase occurs under prolonged treatment with oxygen plasma. The formation of a PdOx (x > 1) species, characterized by a Eb(Pd3d5/2) = 338.0–338.2 eV value that is close to the Pd4+ oxidation state, was also observed. This PdOx species was found to have low thermal stability (T < 400 K). It is proposed that the PdOx species can be localized within the boundaries of crystallites. 相似文献
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Study of nanocrystalline VO2 thin films prepared by magnetron sputtering and post-oxidation 下载免费PDF全文
Nanocrystalline VO2 thin films were deposited onto glass slides by direct current magnetron sputtering and postoxidation. These films undergo semiconductor-metal transition at 70°C, accompanied by a resistance drop of two magnitude orders. The crystal structures and surface morphologies of the VO2 films were characterized by x-ray diffraction (XRD) and atomic force microscope (AFM), respectively. Results reveal that the average grain size of VO2 nanograins measured by XRD is smaller than those measured by AFM. In addition, Raman characterization indicates that stoichiometric VO2 and oxygen-rich VO2 phases coexist in the films, which is supported by x-ray photoelectron spectroscopy (XPS) results. Finally, the optical properties of the VO2 films in UV-visible range were also evaluated. The optical band gap corresponding to 2p-3d inter-band transition was deduced according to the transmission and reflection spectra. And the deduced value, E opt2p-3d = 1.81 eV, is in good agreement with that previously obtained by theoretical calculation. 相似文献
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H. P. Steinrück 《Applied Physics A: Materials Science & Processing》1994,59(5):517-529
A review of results obtained by Angle-Resolved UV-Photoelectron Spectroscopy (ARUPS) using linearly polarized synchrotron radiation is presented for two model systems, ethylene/Ni and benzene/Ni. It is shown that for these systems detailed conclusions concerning adsorbate/substrate and adsorbate/adsorbate interactions can be derived from ARUPS spectra using symmetry selection rules, and in combination with model calculations. In particular, electronic structure, bonding, orientation and symmetry of the adsorbates in dilute and saturated layers will be discussed. It is shown that at high adsorbate coverages lateral interactions in the adsorbate layer play a dominant role. Steric effects in densely packed layers can lead to a reorientation of the molecules as compared to the orientation of the single molecules. The ARUPS spectra of well ordered, densely packed layers exhibit significant (up to 2 eV) dispersion of the various adsorbate bands and allow detailed conclusions on two-dimensional adsorbate band structures. 相似文献
10.
In the present report, CdS and Ag-CdS nanoparticles were synthesized using cysteine as a capping agent. Surface properties CdS and Ag-CdS nanoparticles were studied by X-ray photoelectron spectroscopy (XPS). XPS study of CdS nanoparticles was carried out as a function of pH and for a refluxed sample at pH 11.2. Effect of dopant concentration on surface properties of Ag-CdS nanoparticles was also studied for as prepared samples as well as for annealed sample at 2% doping. Effect of pH, dopant concentration, and effect of particle size on different sulfur species present in the system was studied. Features of Cd 3d, S 2p and Ag 3d core level have been discussed in detail. 相似文献
11.
Meyer M Radcliffe P Tschentscher T Costello JT Cavalieri AL Grguras I Maier AR Kienberger R Bozek J Bostedt C Schorb S Coffee R Messerschmidt M Roedig C Sistrunk E Di Mauro LF Doumy G Ueda K Wada S Düsterer S Kazansky AK Kabachnik NM 《Physical review letters》2012,108(6):063007
Two-color (x-ray+infrared) electron spectroscopy is used for investigating laser-assisted KLL Auger decay following 1s photoionization of atomic Ne with few-femtosecond x-ray pulses from the Linac Coherent Light Source. In an angle-resolved experiment, the overall width of the laser-modified Auger-electron spectrum and its structure change significantly as a function of the emission angle. The spectra are characterized by a strong intensity variation of the sidebands revealing a gross structure. This variation is caused, as predicted by theory, by the interference of electrons emitted at different times within the duration of one optical cycle of the infrared dressing laser, which almost coincides with the lifetime of the Ne 1s vacancy. 相似文献
12.
Robert Mark Friedman R.I. Declerck-Grimee J.J. Fripiat 《Journal of Electron Spectroscopy and Related Phenomena》1974,5(1):437-446
ESCA was used to monitor the chemical modification of a series of commercial cobalt-molybdenum-alumina hydrodesulfurization catalysts subjected to different reaction conditions. In the oxide form, the surface phase MoO3 and CoAl2O4. Reduction and sulfiding using a 15:85 H2S/H2 mixture shifts the molybdenum peaks to the region of MoS2. Part of the cobalt is apparently reduced and sulfided, but this species is susceptible to re-oxidation by moist air. The supported cobalt which is not changed by this treatment is interpreted as actually being CoAl2O4 formed by interaction of the dispersed material with the support during calcination. The presence of this aluminate phase seems to be important for the stability of the catalyst under the harsh conditions of industrial usage. Reduction of the oxide form by pure hydrogen leaves the molybdenum binding energy unchanged and shifts the cobalt peak to higher binding energy. This is interpreted as arising from a shift in reference level and it is concluded that the actual transformation 相似文献
13.
W H Madhusudan Sheelavathi Kollali P R Sarode M S Hegde P Ganguly C N R Rao 《Pramana》1979,12(4):317-329
X-ray and ultraviolet photoelectron spectroscopy as well as x-ray absorption spectroscopy have been employed to investigate
transition metal oxide perovskites of the general formula ABO3 (A = La or rare-earth ion, B=trivalent transition metal ion). Systematics in the core levels and in the valence bands in
the series of LaBO3 compounds have been discussed. Lanthanum chemical shifts in the x-ray absorption spectra in this series show interesting
trends. Photoelectron spectra of the solid solutions, LaNi1−x
Co
x
O3, LaNi1−x
Fe
x
O3 and LaFe1−x
Co
x
O3 show that the rigid band model is applicable to these systems. It is shown that x-ray photoelectron spectroscopy can be employed
to identify multiple oxidation states of transition metal ions in oxide perovskites.
Communication No. 30 from the Solid State and Structural Chemistry Unit.
An erratum to this article is available at . 相似文献
14.
Chemical compositions of the alloys of CuNi (Cu0.10Ni0.90, Cu0.30Ni0.70, Cu0.70Ni0.30) and BiSb (Bi0.80Sb0.20, Bi0.64Sb0.34, Bi0.55Sb0.45) are determined by X-ray photoelectron spectroscopy. The stoichiometries are determined and are compared with the bulk compositions.
Possible sources of systematic errors contributing to the results are discussed. Errors arising out of preferential etching
in these alloys have been investigated. It has been inferred from such studies that the preferential etching does not enrich
the surface composition with a particular component for the two systems reported here. Quantitative results of CuNi system
indicate that the surface regions of the Cu0.70Ni0.30 alloy is Cu-rich, although no such evidence is observed in case of BiSb system. 相似文献
15.
利用低速高电荷态Xeq+和Pbq+离子对在蓝宝石衬底上生长的GaN晶体膜样品进行辐照,并利用X射线光电子能谱(XPS)对样品表面化学组成和元素化合态进行了分析.结果表明,高电荷态离子对样品表面有显著的刻蚀作用;经高电荷态离子辐照的GaN样品表面氮元素贫乏而镓元素富集;随着入射离子剂量和所携带电荷数的增大,Ga—Ga键相对含量增大;辐照后,GaN样品中Ga—Ga键对应的Ga3d5/2电子的束缚能偏小,晶格损伤使内层轨道电子束缚能向低端方向偏移. 相似文献
16.
E. A. Il’inchik 《Journal of Applied Spectroscopy》2008,75(6):883-891
A set of standard compounds for x-ray photoelectron spectroscopy (XPS): KBH4, NaBPh4, and KBF4 has been identified. Literature data on XPS for salts of the anions , , and , the donor-acceptor complexes LBF3, and also their related compounds was analyzed with a view toward the validity of the data.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 886–895, November–December, 2008. 相似文献
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The molecular orientation of Vanadyl-Phthalocyanine (VOPc) grown on alkali halides was studied by Angle-Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS). To avoid charging up of the specimen during ARUPS measurment, thin epitaxial films of alkali halides grown on GaAs (0 0 1) were used as substrates. Photoelectrons emitted from the highest occupied molecular orbital band of VOPc showed strong angular distribution leading to the conclusion that the molecules stay almost parallel on the surface. This was in accordance with the expectation based on the reflection high-energy electron diffraction analysis of the film. 相似文献
20.
David Mehaffy Paul R. Keller James W. Taylor Thomas A. Carlson Frederick A. Grimm 《Journal of Electron Spectroscopy and Related Phenomena》1983,28(3):239-247
Angle-resolved photoelectron spectra of benzene have been recorded using synchrotron radiation as the photon source. From these results the angular dis the first three orbitals; 1e1g(π), 3e2g (σ) and 1a2u(π). Calculations of β employing the MS Xα method have also b and theory for the first two orbitals is excellent. Poor agreement in the core of the third orbital is believed to be due to overlap of the second and has been verified by data obtained for perfluorobenzene. The universality of the energy dependence of β for π orbitals, noted previously for unsatu aromatic systems. The importance of the results for benzene for the future application of angle-resolved photoelectron spectroscopy to complex molecule 相似文献