Abstract
Site-specific x-ray photoelectron spectroscopy together with density functional theory calculations based on the local density approximation have identified the chemical bonding, single-particle matrix element, and many-body effects in the x-ray photoelectron spectrum of corundum . Significant covalent bonding in both the upper and lower lobes of the photoelectron spectrum is found, despite the localized nature of the electrons that are responsible for the Mott behavior. We show that the approximate treatment of correlation dominates the discrepancy between theory and experiment in the near-Fermi-edge region and that many-body effects of the photoemission process can be modeled by Doniach-Šunjić [J. Phys. C 3, 285 (1970)] asymmetric loss. Correlation effects govern the relative intensity and energy position of the higher level electron bands, and many-body effects dominate the “tail” region of both the upper and lower lobes of the photoemission spectrum.
- Received 24 January 2007
DOI:https://doi.org/10.1103/PhysRevB.76.165101