title: Spectroscopic characterization of the uranium carbonate andersonite Na2Ca[UO2(CO3)3] x 6H2O.
abstract: The uranium carbonate andersonite Na2Ca[UO2(CO3)3] x 6H2O was synthesized and identified with classical analytical and spectroscopic methods. The classical methods applied were powder X-ray diffraction (XRD), nitric acid digestion, and scanning electron microcopy combined with energy-dispersive spectroscopy (SEM/EDS). To characterize andersonite spectroscopically, time-resolved laser-induced fluorescence spectroscopy (TRLFS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) were used. Natural and synthetic andersonite samples were characterized with the nondestructive TRLFS by six fluorescence emission bands at 470.6, 486.1, 505.4, 526.7, 549.6, and 573.9 nm. In addition, andersonite was characterized by FT-IR measurements by the appearance of the asymmetric stretching vibration of the uranyl cation [v3(UO2(2+))] at 902 cm(-1) with a shoulder at 913 cm(-1). XPS measurements verified the composition of the synthetic andersonite sample. The measured intensity ratios of the XPS lines agree with the stoichiometry of Na2Ca[UO2(CO3)3] x 6H2O. The XPS features of the inner valence molecular orbitals are characteristic of the [UO2(CO3)3]4- structural moiety. These spectroscopic methods can be used to identify in a fingerprinting procedure secondary U(VI) phases in mixtures with other phases or as thin coatings on mineral and rock surfaces.
authors.affiliation: Institut für Radiochemie, Forschungszentrum Rossendorf, 01314 Dresden, Germany. amayri@uni-mainz.de
authors.forename: Samer
authors.initials: S
authors.lastname: Amayri
authors.forename: Thuro
authors.initials: T
authors.lastname: Arnold
authors.forename: Tobias
authors.initials: T
authors.lastname: Reich
authors.forename: Harald
authors.initials: H
authors.lastname: Foerstendorf
authors.forename: Gerhard
authors.initials: G
authors.lastname: Geipel
authors.forename: Gert
authors.initials: G
authors.lastname: Bernhard
authors.forename: Andreas
authors.initials: A
authors.lastname: Massanek
mesh_terms: D002254:Carbonates / Q000032:analysis* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011848:Radioactive Pollutants / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D017974:Uranium Compounds / Q000032:analysis* / Q000737:chemistry
chemical_list: D002254:Carbonates; D011848:Radioactive Pollutants; D017974:Uranium Compounds