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  • 1
    Electronic Resource
    Electronic Resource
    Energy loss near-edge structure for materials containing light elements by reflection electron energy loss spectroscopy (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 25-27 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A reflection electron energy loss spectroscopy system has been developed to investigate local surface atomic structures around light elements such as C, N, and O. Electrons scattered inelastically on a surface with a small scattering angle are energy analyzed. This system was used to measure energy loss near-edge structures (ELNESs) for materials such as BN, graphite, and NiO. The comparison between ELNES and x-ray absorption near edge structure suggests that the ELNES is useful for the atomic structure analyses of surfaces. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114169
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  • 2
    Electronic Resource
    Electronic Resource
    Path-integral approach to Debye–Waller factors in EXAFS, EELS and XPD for cubic and quartic anharmonic potentials (2000)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 7 (2000), S. 95-102 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In this paper thermal effects in extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron diffraction (XPD) due to atomic vibration in cubic and quartic potentials are studied by use of Feynman's path-integral approach. This approach can be applied to strongly anharmonic systems where the cumulant analyses break down. It is closely related to the well known classical approach which is only valid at high temperature. The phase of the thermal factor plays an important role both in EXAFS and XPD analyses for the asymmetric potential with strong anharmonicity. At low temperature the cumulant expansion up to the second order for the thermal damping function agrees well with the self-consistent result, but up to higher orders should be taken into account for the phase function. At high temperature the result from self-consistent calculations shows the characteristic behaviour: the thermal damping function is negative in the high-k region for both strongly and weakly anharmonic systems. The cumulant approximation cannot reproduce this behaviour. For the strongly anharmonic systems the quantum result shows qualitatively different behaviour from the classical approximation at low temperature: the former does not show the negative values even in the high-k region, while the latter shows the phase inversion in the amplitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049599015071
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  • 3
    Electronic Resource
    Electronic Resource
    Quantum statistical approach to Debye–Waller factor in EXAFS: application to monatomic fcc systems (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 226-228 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Temperature dependence of the Debye–Waller factors in EXAFS is studied for monatomic fcc lattice by use of the perturbation approach in terms of temperature Green's function. We apply the theory to the temperature dependence of EXAFS for Kr and Ni crystals. Furthermore we make a comparison among sc, bcc and fcc lattices for the present ab initio calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500016575
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  • 4
    Electronic Resource
    Electronic Resource
    Theoretical study of the non-local optical potential in EXAFS spectra (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 207-209 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: We study the optical potential effects on the extended x-ray absorption fine structure (EXAFS) and x-ray photoelectron diffraction (XPD) spectra. For the valence electron optical potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local optical potential for the core electron part based on GW-approximation. In the Br K-edge EXAFS spectra the present optical potential gives rise to the phase difference and the amplitude reduction; the agreement with the experimental result is excellent. In the N-1s XPD spectra for N2/Ni(100), the spherical wave effects enhance the effects due to the optical potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500019221
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  • 5
    Electronic Resource
    Electronic Resource
    X-ray absorption fine structure of V2O5 and LixV2O5 (1998)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 5 (1998), S. 1146-1148 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Vanadium K-edge XAFS measurements of five compounds were carried out. The compounds studied were crystalline V2O5 and four types of LixV2O5 with different insertion levels x, which show different EMFs (2.0–3.4 V). The EXAFS data analysis shows no remarkable difference in the V—O distances in the five compounds, showing that the structure of the VO5 square pyramids changes only slightly as lithium atoms are intercalated into the V2O5. In the XANES spectra, three peaks are observed for crystalline V2O5 and LixV2O5 (3.4 V). When the EMF is decreased, the intensity difference between the first and second peaks disappears and the third peak shifts to lower energy. The XANES data were analysed using full multiple-scattering calculations. In the calculated spectra the intensity of the first peak increases as the V2O5 intercalates lithium atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049597018670
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  • 6
    Electronic Resource
    Electronic Resource
    Theory of EELFS compared with EXAFS for catalysis study (1993)
    Springer
    Catalysis letters 20 (1993), S. 149-157 
    Details
    ISSN: 1572-879X
    Keywords: EELFS theory ; EXAFS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We discuss the similarity and the difference between EXAFS and EELFS for catalysis study based on the theory developed by the present authors. The information obtained from small-and large-angle scattering EELFS is quite different, and the former setup is recommended for catalysis study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00772607
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  • 7
    Electronic Resource
    Electronic Resource
    EELFS as a new tool of local structural characterization of solid surfaces (1993)
    Springer
    Catalysis letters 20 (1993), S. 159-168 
    Details
    ISSN: 1572-879X
    Keywords: EELFS ; ELNES ; local surface structure ; momentum transfer ; O/Ni(100) ; O/W(100)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new apparatus to obtain information on local structures and chemical states of solid surfaces has been constructed, with which we measure electron energy-loss fine structures (EELFS), excited by electrons of a few keV incident at a grazing angle. We describe results about O/Ni(100) and O/W(100) systems, where we extensively take advantage of anisotropy in regard to momentum transfer of the probe electron and high surface sensitivity of this technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00772608
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  • 8
    Electronic Resource
    Electronic Resource
    EXAFS characterization of bimetallic Pt–Pd/SiO2–Al2O3 catalysts for hydrogenation of aromatics in diesel fuel (1999)
    Springer
    Catalysis letters 63 (1999), S. 27-33 
    Details
    ISSN: 1572-879X
    Keywords: Pt–Pd bimetallic catalysts ; aromatic hydrogenation ; diesel fuel ; EXAFS ; active site ; Pd species dispersed on Pt particle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bimetallic Pt–Pd/SiO2–Al2O3 catalysts exhibited much higher activities in aromatic hydrogenation of distillates than monometallic Pt/SiO2–Al2O3 and Pd/SiO2–Al2O3 catalysts. The studies of extended X‐ray absorption fine structure (EXAFS) indicated that there was an interaction between Pt and Pd in the Pt–Pd/ SiO2–Al2O3 catalyst. Furthermore, from the EXAFS, it was assumed that the active metal particle on the Pt–Pd/SiO2–Al2O3 catalysts is composed of the “Pd dispersed on Pt particle” structure. Regarding both the activities of aromatic hydrogenation and the EXAFS results, it was concluded that the Pd species dispersed on Pt particles were responsible for the high activity of the bimetallic Pt–Pd/SiO2–Al2O3 catalysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019008803028
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrodesulfurization of tetrahydrothiophene over evaporated Mo, Co and Mo–Co model catalysts (1999)
    Springer
    Catalysis letters 63 (1999), S. 21-26 
    Details
    ISSN: 1572-879X
    Keywords: hydrodesulfurization of tetrahydrothiophene ; Mo model catalyst ; Co model catalyst ; Mo–Co model catalyst ; hydrodesulfurization over Mo ; hydrodesulfurization over Co ; hydrodesulfurization over Mo–Co
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrodesulfurization (HDS) of tetrahydrothiophene was studied over model catalysts prepared by deposition of Co and Mo thin films on a stainless‐steel foil covered with graphite. There are three main findings: (1) the nominal turnover rate for the HDS reaction is approximately constant and independent of the Co to Mo ratio, (2) the main product was 1,3‐butadiene for cobalt and 1,3‐butadiene and 1‐butene for molybdenum, and (3) the reaction is not poisoned by sulfur. The surfaces were characterized by Auger electron spectroscopy (AES) before and after reaction. The reactions were carried out under 2.6 kPa of tetrahydrothiophene and 100 kPa of H2 at 613 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019048417140
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  • 10
    Electronic Resource
    Electronic Resource
    XAFS theory studied by closed-path Green's function (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 76-80 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The basic framework of X-ray absorption fine structure (XAFS) theory is formulated by use of the non-equilibrium Keldysh–Green function, which presents a unified view of XAFS spectra at zero and nonzero temperature. In particular, the relation between the scattering Green's function and the retarded Green's function Gr is discussed, along with resonance effects in XAFS. The latter effects give rise to unexpected peaks within one-electron theory. Loss effects, both intrinsic and extrinsic, are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500018495
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