X-ray resonant Raman scattering in NiO: Resonant enhancement of the charge-transfer excitations

An energy loss feature with energy transfer close to the anion-to-cation charge-transfer energy of NiO is observed in the inelastic-x-ray-scattering spectrum as the incident x-ray energy is tuned through the Ni K absorption edge of NiO. The inelastic-scattering cross section shows large resonant enhancement and strong incident energy dependence. These observations are interpreted using a configuration-interaction cluster model of NiO. {} 1996 The American Physical Society.