RESONANT PHOTOELECTRON-SPECTROSCOPY ON NIO

Resonant photoelectron spectroscopy studies have been performed on the NiO valence band at photon energies corresponding to the Ni 2p, 3p, a nd O 1s absorption thresholds. Strong resonances are seen in the vicin ity of the Ni 2P threshold, which confirm earlier conclusions from the weaker resonances seen at the Ni 3p threshold. No valence-band resona nce is observed at the O 1s threshold. The analysis of this data confi rms the picture of NiO as a strongly correlated charge-transfer insula tor by identifying the highest-lying states as being of mainly 3d(8)L final-state character. The existence of localized excited Ni states, a s well as the delocalized nature of the O states, are confirmed. Compa risons with the configuration-interaction model and quasiparticle calc ulations are also made.