Experimental and\nTheoretical X‑ray Absorption\nNear Edge Structure Study of UO<sub><i>x</i></sub> Systems\nat the U L<sub>3</sub> Edge

Uranium forms a large number of oxides and its electronic\nstate\nin them is of great fundamental interest. We employ X-ray absorption\nspectroscopy at the U L<sub>3</sub> edge to differentiate between\nmixed oxide phases in uranium compounds. By combining experimental\nXANES spectra with theoretical modeling using the FEFF code, we analyze\nfive uranium oxides: UO<sub>2</sub>, U<sub>4</sub>O<sub>9</sub>, U<sub>3</sub>O<sub>8</sub>, UO<sub>3</sub>, and U<sub>3</sub>O<sub>7</sub>. Our study reveals how variations in spectral features correspond\nto changes in oxidation states, local structure, and electronic information.\nThese findings demonstrate a study that consolidates and systematically\ncompares the entire series UO<sub><i>x</i></sub>, providing\nanalysis of changes in electronic structure as a function of oxidation\nstate and local structure which is important for nuclear materials\nresearch.