Spatial distribution of photoelectrons participating in formation of x-ray absorption spectra

Abstract

Interpretation of x-ray absorption near-edge structure (XANES) experiments is often done via analyzing the role of particular atoms in the formation of specific peaks in the calculated spectrum. Typically, this is achieved by calculating the spectrum for a series of trial structures where various atoms are moved and/or removed. A more quantitative approach is presented here, based on comparing the probabilities that a XANES photoelectron of a given energy can be found near particular atoms. Such a photoelectron probability density can be consistently defined as a sum over squares of wave functions which describe participating photoelectron diffraction processes, weighted by their normalized cross sections. A fine structure in the energy dependence of these probabilities can be extracted and compared to XANES spectrum. As an illustration of this novel technique, we analyze the photoelectron probability density at the Ti K pre-edge of TiS 2 and at the Ti K edge of rutile TiO 2 .To be published in Physical Review B, tentatively scheduled for 15 May 2002 issue. 78.70.Dm

Similarities and Differences Between XANES Spectra at Analogous Edges of Ternary Semiconductors CuGaSe2, ZnGeAs2 and CuFeS2

“…The relative roles of individual atomic sites in the formation of a particular spectral peak can be quantitatively assessed by comparing the wave function probability densities (WFPD) around those sites [8]. By performing this analysis for all the three edges, we found that the excited photoelectron is located almost exclusively on Fe atoms at the pre-peak energy; the calculated WFPD around the Fe sites is by three orders of magnitude higher than around any of the Cu or S sites.…”

“…In order to facilitate the interpretation of the pre-edge region in CuFeS 2 , wave function probability densities associated with the excited photoelectron were calculated in the RSMS formalism [8]. In that way, one can gain a well-defined picture of the spatial distribution of the photoelectrons which participate in the formation of specific XANES features.…”