Resonant photoemission as a tool to study f and d electrons in actinide compounds

Using synchrotron radiation in the energy range 60≤hν≤130 eV, we have measured hν-dependent photoemission energy distribution curves and constant-initial-state spectra from single crystals of UₓTh_1-xSb, UTe, UO₂, and UPd₃. The U $5f$ and U and Th $6d$ conduction bands, as well as the Sb and Te $5p$ valence-band emission, all exhibit Fano-type resonance behavior at the $5d$ core ionization thresholds. The $5f$ emission shows the strongest intensity variation, which can be explained by the super-Coster-Kronig character of the decay of the autoionizing core excited state. Thus f and d emission features in the photoemission spectra are unambiguously identified by their different resonance behavior. It is concluded that the spectra are dominated by localized $5f$ states in all of these compounds.