An Emission Spectral Study of Uranyl Ion Binding to α-Alumina

H.D. Burrows, S.J. Formosinho, M.A. Pedrosa

The effect of binding by α-alumina is examined on the luminescence spectrum of the uranyl ion. At relatively low concentrations, luminescence studies are complicated by the overlap of the uranyl luminescence and the relatively intense scattering bands of the α-alumina. The presence of uranyl ion is shown to lead to a considerable reduction in the intensity of this scattering, and comparison of emission spectra of this sample with those of alumina, uranyl nitrate and an alumina/uranyl nitrate suspension, followed by computer analysis of the common bands allows an idea of the probable uranyl emission spectrum under these conditions. At high uranyl concentrations less interference from the scattering bands is observed. X-ray diffraction of this sample shows uranyl binding without changing the alumina structure, but with modifications in the lattice dimensions. The room temperature emission spectrum of this sample is very similar to that of uranyl nitrate hexahydrate. In addition, certain other bands are observed which are probably due to Raman scattering. Isopropanol is shown to quench this emission, indicating that solvent access is possible to the uranyl binding site. Luminescence lifetime studies indicate a non-exponential decay, and suggest the possibility of uranyl ion being bound to more than one site. Support for this comes from emission spectra obtained at 77K.

Journal of Molecular Structure 143, 223-226 (1986)

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