Resonant soft x-ray Raman scattering of NiO

Resonant soft x-ray Raman scattering measurements on NiO have been made at photon energies across the Ni 2p absorption edges. The details of the spectral features are identified as Raman scattering due to d-d and charge-transfer excitations. The spectra are interpreted within the single-impurity Anderson model, including multiplets, crystal-field and charge-transfer effects. At threshold excitation, the spectral features consists of triplet-triplet and triplet-singlet transitions of the 3d⁸ configuration. For excitation energies corresponding to the charge-transfer region in the Ni 2p x-ray absorption spectrum of NiO, the emission spectra are instead dominated by charge-transfer transitions to the 3d⁹\underline L^-1 final state. Comparisons of the final states with other spectroscopical techniques are also made.