Local symmetry influence on the formation of X-ray absorption near edge structure in KBr and RbCl

X-ray absorption near edge structure (XANES) of the Br and Rb K-edge of high-pressure (B2) phase of KBr and RbCl has been analyzed. We have used a full multiple-scattering method to investigate the conduction band structure of KBr and RbCl. Theoretical K-edge absorption spectra obtained over a large energy interval were used to analyze experimental data. Like in the case of low-pressure (B1) phase, XANES is found to be determined by the multiple scattering of the photoelectron in a large size cluster (30 or more atoms). For the energy interval up to 50 eV above the main edge, the single-scattering approximation seems to be less satisfactory. Comparative analysis of XANES of two different crystal phases made it possible to conclude on the role of local symmetry around absorbing site and characteristics of surrounding atoms in the formation of XANES and conduction band of compounds investigated.