Role of Spin-Orbital Splitting of 5f-Orbitals of Uranium Atom in the Formation of Its Chemical State

Abstract

ABSTRACTChemical shifts (ChSh) of nine emission lines of the uranium L-series in uranium oxides UO2+x (x=0−1) with respect to UO2 were studied by using a precise crystal-diffraction X-ray spectrometer and the changes in energy of spin-orbital splitting (SOS) − Δδnl± of inner nl-orbitals of the uranium atom were calculated from the data of ChSh of spin-doublet lines. For UO2+x oxides, a linear decrease in Δδnl± values with increasing degree of uranium oxidation was found.On the basis of the comparison of experimental Δδnl± values with Dirac-Hartree-Fock atomic calculations, it was concluded that the observed variations in Δδnl± values are due to the redistribution of electron and spin density between the 5f7/2- and 5f5/2-levels of the fine structure of the uranium atom without changes in atomic charge state.