High-pressure effects on L_III-XANES spectra of uranium compounds

Abstract

Abstract X-ray absorption near-edge structure spectra at the U-LIII threshold are presented for UTe, UN, and UC as a function of external pressure up to =35 GPa. In all cases, the white-lines (WL) shift to higher energies with increasing pressure due to increasing 5f-delocalization, i.e. decreasing 5f occupancy. The strongest change in WL energy for a given relative change in lattice volume is observed for We, the most localized compound studied. In addition, structural phase transitions are found to lead to discontinuities in the pressure derivatives of the WL energy.