title: Spectroscopic identification of ternary Cm-carbonate surface complexes.
abstract: The influence of dissolved CO(2) on the sorption of trivalent curium (Cm) on alumina (gamma-Al(2)O(3)) and kaolinite was investigated by time resolved laser fluorescence spectroscopy (TRLFS) using the optical properties of Cm as a local luminescent probe. Measurements were performed at T < 20 K on Cm loaded gamma-Al(2)O(3) and kaolinite wet pastes prepared in the absence and presence of carbonate in order to pictorially illustrate any changes through a direct comparison of spectra from both systems. The red-shift of excitation and emission spectra, as well as the increase of fluorescence lifetimes observed in the samples with carbonate, clearly showed the influence of carbonate and was fully consistent with the formation of Cm(III) surface species involving carbonate complexes. In addition, the biexponential decay behavior of the fluorescence lifetime indicated that at least two different Cm(III)-carbonate species exist at the mineral-water interface. These results provide the first spectroscopic evidence for the formation of ternary Cm(III)-carbonate surface complexes.
authors.affiliation: Laboratory for Waste Management, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. maria.marques@psi.ch
authors.forename: M Marques
authors.initials: MM
authors.lastname: Fernandes
authors.forename: T
authors.initials: T
authors.lastname: Stumpf
authors.forename: B
authors.initials: B
authors.lastname: Baeyens
authors.forename: C
authors.initials: C
authors.lastname: Walther
authors.forename: M H
authors.initials: MH
authors.lastname: Bradbury
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide; D002254:Carbonates / Q000737:chemistry*; D003476:Curium / Q000737:chemistry*; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D002254:Carbonates; D000537:Aluminum Oxide; D003476:Curium