Experimental and Theoretical X-ray Absorption Near Edge Structure Study of UOx Systems at the U L3 Edge.

Uranium forms a large number of oxides and its electronic state in them is of great fundamental interest. We employ X-ray absorption spectroscopy at the U L₃ edge to differentiate between mixed oxide phases in uranium compounds. By combining experimental XANES spectra with theoretical modeling using the FEFF code, we analyze five uranium oxides: UO₂, U₄O₉, U₃O₈, UO₃, and U₃O₇. Our study reveals how variations in spectral features correspond to changes in oxidation states, local structure, and electronic information. These findings demonstrate a study that consolidates and systematically compares the entire series UO_x, providing analysis of changes in electronic structure as a function of oxidation state and local structure which is important for nuclear materials research.