Spectroscopic Verification of the Mineralogy of an Ultrathin Mineral Film on Depleted Uranium


Spectroscopic Verification of the Mineralogy of an Ultrathin Mineral Film on Depleted Uranium

Baumann, N.; Arnold, T.; Foerstendorf, H.; Read, D.

The alteration of a depleted uranium (DU) disc in contact with a synthetic pore water, as simulant for fertilized agricultural soil, was studied by exposing the DU to a Ca-phosphate solution (2.5 • 10−3 M Ca, 1 • 10−3 M P). Within 12 months this contact resulted in the formation of a thin film of a secondary uranium mineral on the metallic DU. The reaction product was analysed both with time-resolved laser-induced fluorescence spectroscopy (TRLFS) and infrared spectroscopy (IR). The TRLFS spectra obtained were compared with spectra of natural occurring uranium reference minerals which could have formed under the specified experimental conditions. IR was used as a complementary analytical technique for spectroscopic characterization of the natural minerals and of the unknown mineral film on DU. Both techniques identified the reac-tion product on DU as a U(VI) phosphate phase, but only TRLFS provided its unequivo-cal identification as meta-autunite based on the positions of the fluorescence emission maxima at 487.8, 502.0, 523.6, 547.0, 572.1, and 600.6 nm and two fluorescence lifetimes of 410 ± 15 ns and 3300 ± 310 ns. These findings demonstrate the enhanced performance and sensitivity of the TRLFS technique for mineralogical characterization of thin sur-face films.

  • Environmental Science & Technology 42(2008)22, 8266-8269

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Publ.-Id: 11123