Electronic structure investigation of CoO by means of soft x-ray scattering

The electronic structure of CoO is studied by resonant inelastic soft x-ray scattering spectroscopy using photon energies across the Co $2p$ absorption edges. The different energy-loss structures in the Raman scattering spectra are identified as due to $d-d$ and charge-transfer excitations. For excitation energies close to the $L_3$ resonance, the spectral features are dominated by quartet-quartet and quartet-doublet transitions of the ${3d}^7$ configuration. At excitation energies corresponding to the satellites in the Co $2p$ x-ray-absorption spectrum of CoO, the emission features are instead dominated by charge-transfer transitions to the ${3d}^8{\underset{¯}{L}}^{-1}$ final state. The spectra are interpreted and discussed with the support of simulations within the single-impurity Anderson model with full multiplet effects which are found to yield consistent spectral functions to the experimental data.