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51.
O. Zaharko C. Meneghini A. Cervellino E. Fischer 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):207-213
The local structure of cobalt and nickel in single crystals of decagonal quasicrystals with composition Al71.5Ni15.5Co13 and Al75Ni14.5Co10.5 have been studied by polarized EXAFS. Significant differences between the Ni and Co local environments have been detected.
The effective absence of the 4 ? periodicity along the decagonal axis in these QCs is confirmed and indications about its
reasons are presented.
Received 26 July 2000 and Received in final form 20 October 2000 相似文献
52.
R.E. Benfield D. Grandjean J.C. Dore Z. Wu M. Kröll T. Sawitowski G. Schmid 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):399-402
The structure of nanowires of different metals grown within nanoporous alumina membranes has been studied by EXAFS, WAXS and
high energy X-ray diffraction. Nanowires of gold, silver, copper and iron adopt the lattice structure and bond distances of
the bulk metals. Cobalt nanowires on the other hand were composed of a mixture of hcp phase, stable at room temperature, and
fcc phase, which in bulk cobalt is normally stable only at high temperatures, in a ratio depending on the pore size. The nanowires
are non-continuous but are made of nanocrystallites whose shape and size was found to depend strongly on the metal. All the
metals except gold showed the presence of a preferred orientation which was slight in the case of Ag and Cu but much stronger
in the case of iron and cobalt nanowires.
Received 30 November 2000 相似文献
53.
Calculating core‐level excitations and x‐ray absorption spectra of medium‐sized closed‐shell molecules with the algebraic‐diagrammatic construction scheme for the polarization propagator
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Core‐level excitations are generated by absorption of high‐energy radiation such as X‐rays. To describe these energetically high‐lying excited states theoretically, we have implemented a variant of the algebraic‐diagrammatic construction scheme of second‐order ADC(2) by applying the core‐valence separation (CVS) approximation to the ADC(2) working equations. Besides excitation energies, the CVS‐ADC(2) method also provides access to properties of core‐excited states, thereby allowing for the calculation of X‐ray absorption spectra. To demonstrate the potential of our implementation of CVS‐ADC(2), we have chosen medium‐sized molecules as examples that have either biological importance or find application in organic electronics. The calculated results of CVS‐ADC(2) are compared with standard TD‐DFT/B3LYP values and experimental data. In particular, the extended variant, CVS‐ADC(2)‐x, provides the most accurate results, and the agreement between the calculated values and experiment is remarkable. © 2014 Wiley Periodicals, Inc. 相似文献
54.
A.A. Guda N. Smolentsev J. Verbeeck Y. Zubavichus O.E. Polozhentsev 《Solid State Communications》2011,151(19):1314-1317
ZnO/ZnO:Mn core-shell nanowires were studied by means of X-ray absorption spectroscopy of the Mn K- and L2,3-edges and electron energy loss spectroscopy of the O K-edge. The combination of conventional X-ray and nanofocused electron spectroscopies together with advanced theoretical analysis turned out to be fruitful for the clear identification of the Mn phase in the volume of the core-shell structures. Theoretical simulations of spectra, performed using the full-potential linear augmented plane wave approach, confirm that the shell of the nanowires, grown by the pulsed laser deposition method, is a real dilute magnetic semiconductor with Mn2+ atoms at the Zn sites, while the core is pure ZnO. 相似文献
55.
We report on the near‐edge X‐ray absorption fine structure spectroscopy of the L3 (2p3/2) and L2 (2p1/2) edges for ferromagnetic pure nickel transition metal and show that the L2,3 edge peak intensity and satellite feature at ~6 eV above the L3 edge in nickel increase with increasing nickel film thickness both in the total electron yield and transmission modes. The absorption spectra of nickel metal, however, exhibit strong angular‐dependent effects when measured in total electron yield mode. In addition, we calculated the mean electron escape depth of the emitted electrons (λe), which was found for pure nickel metal to be λe=25 ± 2 Å. We point out the advantages of the total electron yield technique for the study of the L‐edge of 3d transition metals. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
56.
Kaveenga Rasika Koswattage Iwao ShimoyamaYuji Baba Tetsuhiro SekiguchiKazumichi Nakagawa 《Applied Surface Science》2011,258(4):1561-1564
Adsorption behavior of atomic deuterium on a hexagonal boron nitride (h-BN) thin film is studied by photon-stimulated ion desorption (PSID) of D+ and near edge X-ray absorption fine structure (NEXAFS) at the B and N K-edges. After the adsorption of atomic deuterium, D+ desorption yield η(hν) shows clear enhancement at the B K-edge and almost no enhancement at the N K-edge. NEXAFS spectra show a large change in the B K-edge and a small change in the N K-edge after the adsorption. We propose selective adsorption of atomic deuterium on the h-BN thin film based on the experimental results, and mention the effectiveness of applying the PSID method with X-ray to study hydrogen storage materials. 相似文献
57.
The lateral surface diffusion at Si-SiO2 interface has been observed at nanometer scale using photoelectron emission microscopy (PEEM) combined with synchrotron soft X-ray excitation. The samples investigated were Si-SiOx micro-patterns prepared by O2+ ion implantation in Si (0 0 1) wafer using a mask. The lateral spacial resolution of the PEEM system was about 41 nm. The brightness of each spot in the PEEM images changed depending on the photon energy around the Si K-edge, in proportion to the X-ray absorption intensity of the corresponding valence states. It was found that the lateral diffusion occurs by 400-450 °C lower temperature than that reported for the longitudinal diffusion at the Si-SiO2 interface. It was also found that no intermediate valence states such as SiO (Si2+) exist at the Si-SiO2 interface during the diffusion. The observed differences between lateral and longitudinal diffusion are interpreted by the sublimated property of silicon monoxide (SiO). 相似文献
58.
Regan G. Wilks Gap Soo Chang Kyung Hwan Kim Dong Hoon Choi Alexander Moewes 《Journal of Electron Spectroscopy and Related Phenomena》2011,184(7):355-359
Angle resolved near-edge absorption fine structure measurements of the C 1s edge of a film of the star-shaped molecule 4(HPBT) show a high degree of order, with the molecules maintaining a largely planar geometry in an upright configuration. X-ray excited optical luminescence measurements showed a dependence of the luminescence spectrum on the excitation energy, with (0–0), (0–1), and (0–2) vibrational modes being clearly visible when exciting off-resonance; the appearance of these features under off-resonance is attributed to a scattering process that is quenched when the excitation approaches a core absorption resonance. The HOMO–LUMO gap is estimated from the luminescence measurements (2.28 eV), and this value is confirmed by the comparison of the C 1s absorption and C Kα emission spectra. 相似文献
59.
G. Iucci V. Carravetta G. Paolucci A. Goldoni M.V. Russo G. Polzonetti 《Chemical physics》2005,310(1-3):43-49
A joint X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) investigation of the adsorption of phenylacetylene (PA, C6H5CCH) on the surface of Rh(1 0 0) single crystal was carried out by evaporating PA on the clean metal surface in the monolayer and multilayer regimes.
The experimental results indicate that the interaction of the PA molecule with the Rh(1 0 0) surface involves mainly the two carbon atoms of the alkyne moiety; the binding of the alkyne group to the metal surface produces the opening of the triple bond. A comparison with the results obtained for PA adsorption on the surface of Pt (1 1 1) and Cu (1 0 0) is also discussed. 相似文献
60.