Resonant inelastic scattering in localized solid systems by soft X-ray fluorescence spectroscopy

Abstract

An insertion device beamline, BL 8.0 at the ALS, utilizes the radiation from a 5.0 cm period undulator to cover the 100 - 1500 eV photon energy range. In a number of solid systems with localized conduction band states and excitonic states, by tuning the energy of the monochromatic x-rays near the core level absorption edges of cation atoms, a resonant inelastic scattering feature is observed. We have carried out careful studies in various systems. As an example, we present resonant X-ray inelastic scattering spectra from CaF2, CaSi and CaSi2 with distinctive localized empty 3d states, to give a general overview of resonant inelastic scattering observations in these systems. When a core electron is excited into a localized state, it stays there long enough eventually to recombine with the core hole, resulting in resonant elastic peaks. For the inelastic process, the energy loss observed indicates an electronic transition of the valence electron to the localized states in the conduction band accompanying the excitation.