Combining luminescence spectroscopy, parallel factor analysis and quantum chemistry to reveal metal speciation - a case study of uranyl(vi) hydrolysis.

ABSTRACT: This study of aqueous metal speciation is an advanced combination of theoretical and experimental methods. 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 M) 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 region is extreme ligand sensitive and 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. The methodological concept used here is applicable to luminescent metals in general and thus enables acquisition of refined structural and thermodynamical data of lanthanide and actinide complexation.

SUBMITTER: Drobot B 

PROVIDER: S-EPMC5811152 | biostudies-other | 2015 Feb

REPOSITORIES: biostudies-other