Resonant inelastic x-ray scattering study of the electronic structure of Cu2O

A resonant inelastic x-ray scattering study of the electronic structure of the semiconductor cuprous oxide, Cu₂O , is reported. When the incident x-ray energy is tuned to the CuK -absorption edge, large enhancements of the spectral features corresponding to the electronic transitions between the valence band and the conduction band are observed. A feature at 6.5 eV can be well described by an interband transition from occupied states of mostly Cu3d character to unoccupied states with mixed 3d , 4s , and O2p character. In addition, an insulating band gap is observed, and the momentum dependence of the lower bound is measured along the Γ-R direction. This is found to be in good agreement with the valence-band dispersion measured with angle-resolved photoemission spectroscopy.