Resonant photoelectron spectroscopy studies have been performed on the NiO valence band at photon energies corresponding to the Ni 2 p, 3p, and O 1s absorption thresholds. Strong resonances are seen in the vicinity of the Ni 2p threshold, which confirm earlier conclusions from the weaker resonances seen at the Ni 3p threshold. No valence-band resonance is observed at the O 1s threshold. The analysis of this data confirms the picture of NiO as a strongly correlated charge-transfer insulator by identifying the highest-lying states as being of mainly 3d 8 L គ final-state character. The existence of localized excited Ni states, as well as the delocalized nature of the O states, are confirmed. Comparisons with the configuration-interaction model and quasiparticle calculations are also made.
Resonant photoemission spectroscopy was performed on CeIn 3 and CeSn 3 at the 4d-4 f and 3d-4 f core thresholds. Using the different surface sensitivity between the two photon energies, surface and bulk 4 f -photoemission spectra were derived for both compounds. With the noncrossing approximation of the Anderson impurity model, the 4d-4 f resonant spectra together with the surface and bulk spectra were selfconsistently analyzed to obtain the microscopic parameters such as the 4 f -electron energy and the hybridization strength with conduction electrons. The result shows a substantial difference in these parameters between the surface and the bulk, indicating that it is important to take into account the surface effect in analyzing photoemission spectra of Ce compounds. It is also found that the 4 f surface core-level shift is different
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