Mechanisms of near edge fine structure formation in K-edge absorption spectra of oxygen and metal atoms in the perovskite-structure titanates

Full multiple scattering in the cluster approximation with semiempirical MT potential was used for thorough investigation of the near-edge fine structure of Ti and O K spectra from PbTiO3, BaTiO3, CaTiO3 and SrTiO3 crystals. The calculated spectra were shown to be in good agreement with the experiment. The mechanisms underlying the emergence of fine structure elements of the spectra were revealed. Near-edge structure of titanium K spectra was examined in detail. In the general case, this structure was found to have five features of various nature. The quantitative description of near-edge structure requires a model of incomplete shielding of the 1s hole. Substantiation of this model was proposed.