Electronic Structure of Alkaline-Earth Fluorides Studied by Model Clusters. II. Auger-Free Luminescence

Abstract

We present the results of molecular-orbital calculations for BaF₂. The discrete variational (DV) Xα cluster method is applied to calculations of Auger-free luminescence (AFL) spectrum and X-ray absorption near edge structure (XANES). The AFL spectrum is analyzed by making use of level structures of the model cluster. The theoretical spectrum reproduces well the characteristics of the experimental one. Only the physical process corresponding to the 5.6 eV emission in AFL is found to be localized. The X-ray absorption spectrum for Ba O_{2, 3} edge in BaF₂ is calculated and compared with the excitation spectrum of AFL at 5.6 eV in BaF₂. The theoretical absorption spectrum reproduces well the characteristics of the experimental excitation spectrum of AFL in the energy range less than 10 eV from the edge.