XPS investigations on cesium uranates: mixed valency behaviour of uranium

UO 2 surface oxidation by mixtures of water vapor and hydrogen as a function of temperature

“…In Figure 1 the spectra after this last treatment can be observed and its main characteristics are listed in Table III. This spectrum characteristics are attributed to U(IV) as can be seen by comparing UO2 XPS and the ones obtained after T-H2(500) [9,[15][16][17]. Therefore, this last treatment was performed before each subsequent experiment, in order to have UO2 at the sample surface and follow the UO2 surface evolution before and after the experiments.…”

“…a. [9,[15][16][17] b. [21,22] Table III List of the main characteristics of the U 4f band for each T-H2-H2O (i) and T-Ar-H2O treatment realized focusing at the Binding Energy and the FWHM of the U4f7/2 peak, the relative position of the two observed satellites refereed to the U 4f5/2 peak position and the percentage of U(IV), U(V) and U(VI).…”

Many-body effects in the4fx-ray photoelectron spectroscopy of theU5+andIlton1, Bagus2 2005Phys. Rev. B191130View full textAdd to dashboardCite

“…In particular, satellites at 6.5-7, ϳ8.5, and both ϳ4 and ϳ10 eV higher BE than both the 4f 7/2 and 4f 5/2 primary peaks are associated with the tetravalent, pentavalent, and hexavalent oxidation states of U, respectively. [1][2][3] Quantitative values for U 4+ -U 5+ -U 6+ concentrations are usually obtained by curve fitting the main 4f peaks with 2 or 3 components of equal full width at half maximum ͑FWHM͒ or, more rarely, by curve fitting both satellite and core peaks in a coherent model. 4 At least two issues are apparent in such analyses: first, to what extent are the satellite features dependent on the bonding environment and, second, is the assumption of equal component FWHM appropriate?…”

“…As expected, the U 4+ primary peaks are broader and have more associated satellite structure than does U 5+ . A comparison of a synthetic spectrum for U 4+ with the observed XPS of UO 2 indicates that interatomic, solid-state, effects may decrease the multiplet and spin-orbital splitting, relative to the free ion. Notably, the 7 eV satellite characteristic of UO 2 is absent from the calculated XPS of U 4+ .…”

The electrochemical reduction of hydrogen peroxide on uranium dioxide under intermediate pH to acidic conditions

“…The U 4f 7/2 peak was deconvoluted manually with a spreadsheet into contributions of U IV , U V and U VI using published binding energies and the procedure previously described by Santos et al, for which a more extensive description has been published [41]. For this work, the satellite structure [42] in the vicinity of this peak and the behaviour in the valence band region were used to check the validity of the fit.…”