Uranyl(VI) hydrolysis studied by luminescence spectroscopy


Uranyl(VI) hydrolysis studied by luminescence spectroscopy

Drobot, B.; Steudtner, R.; Raff, J.; Brendler, V.; Geipel, G.; Tsushima, S.

Speciation constitutes the basis for actinide complexation studies. These systems can be very complex and challenging especially because of the polynuclear species. An advanced combination of theoretical and experimental methods is proposed here. Continuous wave (CW) and time-resolved laser-induced fluorescence spectroscopy (TRLFS) data of uranyl(VI) hydrolysis were analyzed using parallel factor analysis (PARAFAC). Distribution patterns of five major species were thereby derived under a fixed uranyl concentration (10-5) over a wide pH range from 2 to 11. UV (180 nm to 370 nm) excitation spectra were extracted for individual species. Time-dependent density functional theory (TD-DFT) calculations revealed ligand excitation (water, hydroxo, oxo) in this region and ligand-to-metal charge transfer (LMCT) responsible for luminescence. Thus excitation in the UV is extreme ligand sensitive and highly specific. Combining findings from PARAFAC and DFT the [UO2(H2O)5]2+ cation (aquo complex, 1:0) and four hydroxo complexes (1:1, 3:5, 3:7 and 1:3) were identified. Refined structural and thermodynamical data of uranyl(VI) hydrolysis is thus acquired.

  • Poster
    Second Joint Student Workshop on f-Element Chemistry, 09.-10.06.2015, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22130
Publ.-Id: 22130