Photoacoustic spectroscopy of actinide oxides

Oxidation state determination of uranium in various uranium oxides: Photoacoustic spectroscopy complimented by photoluminescence studies

“…The absorption spectra of the free ions of trivalent actinides and lanthanides in crystals show a remarkable similarity [14,22]. They consist of sharp, clearly separated group of lines.…”

“…These spectra also mask UO 3 spectra. Possible explanation for broad absorption bands for UO 2 in the UV region is the assumption of an electron transfer process which is produced by an electron being transferred from molecular oxygen orbital to a partly filled or empty 5f electron state of the oxidizing central uranium atom [22]. It has been shown that electron transfer bands compete with the 5f n →5f n-1 6d bands, especially in the higher actinides [35].…”

“…Similarly, pentavalent uranium absorption in α and β UF 5 has also been reported in the literature by Hecht et al [15] where the absorption maxima is observed in the near-IR region at 900-1100 nm. Kimura et al in the authors have used free ion energy level diagram for interpretation of the data [22]. In those reports it was observed that, the stoichiometry had almost no influence on the structure of the spectrum which was broad and featureless.…”