X-ray and UV photoemission studies of valence electronic structure of NiO

Abstract

The X-ray and UV photoemission valence band spectra of NiO are interpreted using the molecular orbital theory for the NiO 10− 6 cluster and the sudden approximation (monopole selection rules). They exhibit the effects of crystal field splitting, multiplet splitting, electron shake-up (O 2pe b g→ Ni 3de a g). relaxation and Ni 3dO 2p hybridization. Shake-up satellite data indicate that the NiO optical absorption edge near 4 eV is associated with an O 2p → Ni 3d transition. The NiO valence electronic structure obtained in this work is compared with band structure models of Wilson and Mattheiss.