Direct observation of pure pentavalent uranium in U₂O₅ thin films by high resolution photoemission spectroscopy.

ABSTRACT: Thin films of the elusive intermediate uranium oxide U₂O₅ have been prepared by exposing UO₃ precursor multilayers to atomic hydrogen. Electron photoemission spectra measured about the uranium 4f core-level doublet contain sharp satellites separated by 7.9(1) eV from the 4f main lines, whilst satellites characteristics of the U(IV) and U(VI) oxidation states, expected respectively at 6.9(1) and 9.7(1) eV from the main 4f lines, are absent. This shows that uranium ions in the films are in a pure pentavalent oxidation state, in contrast to previous investigations of binary oxides claiming that U(V) occurs only as a metastable intermediate state coexisting with U(IV) and U(VI) species. The ratio between the 5f valence band and 4f core-level uranium photoemissi

SUBMITTER: Gouder T 

PROVIDER: S-EPMC5974404 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature