On the Role of High‐Order Multiple Scattering Terms in Br K‐Edge XANES of the Ionic Conductor AgBr

Abstract

The role of the multiple scattering terms in the Br K-edge X-ray absorption near edge structure(XANES) spectrum of AgBr is studied. In this system, in spite of the arrangement of atoms in collinear geometry, the first term in the expansion of the absorption coefficient (the single-scattering term) is shown to account for the main features of the experimental spectrum in the range of 80 eV above the absorption threshold. The role of both the large Br-Ag distance 0.289 nm and the short core hole lifetime in reducing the amplitude of multiple scattering terms is discussed. The size of the cluster of neighbor atoms probed by the XANES spectrum is studied: the second shell consisting of twelve Br atoms is shown to give the main contribution to the observed experimental features showing the minor role of the first coordination shell. I ) Sorge str. 5, 344104 Rostov on Don, Russia. ') On leave from the Department of Solid State Physics, Rostov Unversity, Russia.

Electronic structure of RbBr during the phase transition: x-ray absorption near-edge structure analysis

“…Previous analyses of the x-ray absorption near-edge structures (XANESs) in NaCl-type alkali halides have been performed [2][3][4][5], but the most interesting results have been obtained while studying the phase transition in ionic compounds associated with both XANES [6][7][8] and EXAFS [9] regions. Recently, in a series of studies, the analysis of AgBr, KBr, NaBr and RbCl electronic structures using joint experimental and theoretical XANES studies have been made [10][11][12][13]. We have found that for RbCl and KBr the single-scattering model gives one the opportunity of describing only the main features of the absorption spectra within the 50 eV above the K edge.…”