Electron-energy-loss function of and by x-ray photoemission spectroscopy: Theory and experiment

Abstract

We report experimental energy-loss structures in x-ray photoemission spectra of single crystalline (Formula presented) and (Formula presented), and then compare these with theoretical electron-energy-loss functions calculated from first principles using the full-potential linearized augmented plane-wave method in the local-density approximation. The energy-loss structure of core electrons can be approximated by a sum of four components: for (Formula presented) the peaks positioned at 8.0, 13.4, 15.8, and 22.6 eV; for (Formula presented) those positioned at 7.0, 12.0, 14.5, and 21.8 eV. The momentum matrix elements between Bloch functions were evaluated to determine the electron energy-loss functions. The theoretical electron-energy-loss functions agreed fairly well with the experimental one. The experimental peaks positioned at 8.0, 13.4, and 15.8 eV for (Formula presented) and those at 7.0, 12.0, and 14.5 eV for (Formula presented) were assigned to the interband transitions from the valence band to the conduction bands. The peaks at 22.6 eV for (Formula presented) and 21.8 eV for (Formula presented) were ascribed to the electron excitation from the (Formula presented) level to the lower conduction band. © 1998 The American Physical Society.