PNNL

Abstract

Resonant photoelectron spectroscopy can uniquely identify the nature of the complicated many-electron effects that accompany the photo-ionization of an inner-shell core hole. Careful analysis of the photon-energy dependence of the Ni KLL Auger de-excitation spectra at and above the Ni 1s photo-ionization threshold has identified the satellite structure that appears in the Ni photo-ionization spectra of NiO as Ni metal 3d eg ? Ni metal 3d eg and O ligand 2p eg ? Ni metal 3d eg charge-transfer excitations, respectively. These assignments elucidate the conflicting theoretical predictions of the last three decades in addition to other anomalous effects in the spectroscopy of this unique material.