Resonant photoemission as a tool to studyfanddelectrons in actinide compounds

Abstract

Using synchrotron radiation in the energy range $60\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}130$ eV, we have measured $h\ensuremath{\nu}$-dependent photoemission energy distribution curves and constant-initial-state spectra from single crystals of ${\mathrm{U}}_{x}{\mathrm{Th}}_{1\ensuremath{-}x}\mathrm{Sb}$, UTe, U${\mathrm{O}}_{2}$, and U${\mathrm{Pd}}_{3}$. 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.