X-ray absorption fine-structure investigation of the ionic compounds NaBr, KBr and RbCl: full multiple-scattering analysis

Abstract

The x-ray absorption near-edge structures (XANESs) of the Br K edge in NaBr and KBr and the Rb K edge in RbCl have been analysed. In spite of the fact that these compounds have the same type of crystal lattice (NaCl type) the published experimental spectra show different structures. We have used a full multiple-scattering method to investigate the conduction band structures of NaBr, KBr and RbCl. The partial densities of Br and Rb p states in the conduction bands were obtained over a large energy interval for both the ground and the excited states. The latter were used to analyse the experimental data. In contrast with our recent study of AgBr, the Br K XANESs in NaBr and KBr and the Rb K XANES in RbCl are found to be determined by the multiple scattering of photoelectrons in a large cluster (30 or more atoms). We also show that, for the energy interval up to 80 eV above the main edge, the single-scattering approximation in the present study seems to be less satisfactory.