Resonant photoemission study of the electronic structure of CuO and Cu2O.

Abstract

The electronic structures of CuO and ${\mathrm{Cu}}_{2}$O have been investigated by resonant photoemission at the copper 3p threshold. The experimental data from CuO are compared with the results of a cluster calculation. From this analysis we confirm the dominant ${\mathit{d}}^{8}$ character of the states between 8 and 16 eV, and that singlet and triplet final states behave quite differently at the (3p\ensuremath{\rightarrow}3d) resonance. It is necessary to specify the multiplet state when calculating the d-d Coulomb interaction in this case since the total energy spread of the ${\mathit{d}}^{8}$ multiplets is about 8 eV. The results confirm the charge-transfer nature of the band gap in CuO. The resonance behavior in ${\mathrm{Cu}}_{2}$O is explained in terms of strong O 2p--Cu 4(sp) hybridization.