Type: Article
Publication Date: 2010-05-05
Citations: 47
DOI: https://doi.org/10.1103/physrevb.81.195104
Nonresonant inelastic x-ray scattering (NIXS) experiments have been performed to probe the $5d\text{\ensuremath{-}}5f$ electronic transitions at the uranium ${O}_{4,5}$ absorption edges in several systems characterized by either a localized or itinerant character of the $\text{U}\text{ }5f$ electrons, namely, ${\text{UO}}_{2}$, USe, US, and elemental uranium in the $\ensuremath{\alpha}$ form. For small values of the scattering vector $q$, the spectra are dominated by dipole-allowed transitions encapsulated within the ill-defined giant resonance, whereas for higher values of $q$ the multipolar transitions of rank $k=3$ and 5 give rise to strong and well-defined multiplet peaks in the pre-edge region. The origin of the observed nondipole multiplet structures is explained on the basis of many-electron atomic spectral calculations. The results obtained demonstrate the high potential of NIXS as a bulk-sensitive technique for the characterization of the electronic properties of actinide materials. The different U compounds show strong variations in the ${O}_{5}$ structure that can be correlated with the ground-state properties of the materials.