Electronic structure of Ce and its intermetallic compounds

We report the core-level x-ray photoelectron spectroscopy spectra of 30 intermetallic compounds of La and Ce. The results are discussed in the light of calculations using the Anderson impurity model of the $4f$ levels and including the degeneracy of the $4f$ levels. The comparison allows us to derive values for the coupling between the f levels and the conduction states Δ and the number of $4f$ electrons nf. We find Δ to be up to {~} 150 meV in some Ce intermetallic compounds, and find nf to range from {~}0.8-1.1. We cannot reconcile the core-level results with the traditional promotional model in which Δ was assumed to be 10 meV or less and the f-electron count could range from 1 down to zero in Ce intermetallic compounds.