Chemical bonding between uranium and oxygen in U6+-containing compounds

Highlights: ► Core level spectroscopy is sensitive to U–O chemical bonding in U6+-oxides. ► Binding energy difference ΔBE = BE (O 1s) – BE (U 4f7/2) is a key parameter. ► ΔBE increases with increasing mean U–O bond distance in U6+-compounds. - Abstract: Electronic parameters of a suite of hexavalent uranium compounds measured with X-ray photoelectron spectroscopy (XPS) have been collected. The binding energy difference, ΔBE = BE (O 1s) – BE (U 4f7/2), was used to characterize the valence electron transfer on the formation of the U–O bonds. The chemical bonding effects were considered on the basis of published structural and XPS data for U6+-bearing compounds. An empirical relationship is obtained between ΔBE and the mean U–O bond distance, L(U–O).