Showing papers on "XANES published in 1981"
TL;DR: In this article, the authors present a flexible theory based on a full multiple scattering cluster calculation, which can be used to extract such information in ordered, disordered and other complex systems now being studied using synchrotron radiation.
144 citations
TL;DR: Spectra for the two metals have been analysed using the new multiple scattering formalism and unlike a conventional band structure approach it does not require structural periodicity but works from the local arrangement of atoms.
Abstract: The measurement of X-ray absorption fine structure of metals— both in the extended region (EXAFS) as well as in the near edge region (XANES)—has been widely discussed (see refs 1–6 for Cu and refs 7–9 for Mn). The recent availability of intense X-ray fluxes from storage rings has usually been exploited for EXAFS leaving the XANES often with poorer resolution than earlier work performed on conventional sources (for example, compare the near edge structure for copper in ref. 1 with refs 3 or 6). In addition, whilst the theory and analysis of EXAFS is relatively well-established2,10, a theory for the strong scattering regime near to the absorption edge has only recently been developed11. We report here the first high resolution XANES spectra for Cu and Mn which were performed at the SRS storage ring at Daresbury. Although both metals have close-packed structures consisting of atoms of similar size their local atomic structure is different in detail. Significant differences are found in their respective XANES reflecting the senstivity of this region of the X-ray absorption fine structure to the local atomic structure. Spectra for the two metals have been analysed using the new multiple scattering formalism. This is a real space calculation and unlike a conventional band structure approach it does not require structural periodicity but works from the local arrangement of atoms.
103 citations
TL;DR: In this article, X-ray absorption near edge structures (XANES) of TmSe and Tm2+ ions were used for the analysis of the conduction states near the Fermi level.
Abstract: L3 and L1 X-ray absorption spectra of single crystals of TmSe and Tm metal were measured at the synchrotron radiation facility PULS using the Frascati storage ring Adone. Valence fluctuations in TmSe appear from the analysis of the X-ray absorption near edge structures (XANES). The XANES of TmSe shows two well resolved 'giant resonances' at the L3 threshold due to 2p to 5, epsilon d* transitions localised on the Tm3+ and Tm2+ ions. The joint analysis of the L1 and L3 edges gives information on the symmetry of the conduction states near the Fermi level. The effects of the core-hole-induced relaxation on the measured intermediate valence are not important in Tm compounds. The values of the intermediate valence of Tm in TmSe can be extracted from XANES in contrast to what seems to be the case for Ce in intermediate valence Ce compounds.
23 citations