Abstract
The linearly polarized Cu K-edge x-ray-absorption near-edge structure (XANES) of (Bi 2:2:1:2) has been measured, and the spectra are interpreted by the multiple-scattering approach in real space. The polarized spectra can be predicted in terms of a one-electron dipole (Δl=+1) transition Cu 1s→εp, probing the unoccupied p-like (l=1) density of states projected on the Cu site with orbital angular momentum =0 in the E∥z spectra, and the =1 in the E⊥c spectra. Therefore we show that the electronic structure of the high-energy conduction bands, beyond the Cu 3d band, are well described in terms of the one-electron approximation. Final-state effects induced by the core hole have been studied and calculated. A satellite 7 eV above the main K-XANES peak in both polarizations is shown to be a multielectron shake-up excitation, and it is enhanced going into the insulating phase. Structural information on the copper site in and in has been extracted from XANES spectra, providing evidence for the decrease of the Cu-O distance in the metallic phase.
- Received 7 January 1991
DOI:https://doi.org/10.1103/PhysRevB.44.4560
©1991 American Physical Society