Competition between resonant Raman scattering and fluorescence at the L3-edges with final 3s hole in CoO and in NiO

Abstract

Abstract We present results on inelastic photon scattering in NiO and CoO in the L 3 threshold region ending with a final 3s hole i.e. 2p 6 3d n →2p 5 3d n +1 →2p 6 3d n +1 3s 1 . The spectra show the presence of Raman features dispersing with the incident photon energy and of a strong feature at constant outgoing photon energy. In CoO the results show that this constant energy feature is present only when the core excitation is 2–3 eV above the core absorption thresholds. This supports a simple model based on the energy loss due to the creation of electron hole pairs across the gap. This mechanism can convert the intermediate excited state into a state of lower energy decaying with the emission at constant photon energy. The implications of these results are briefly discussed.