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Abstract  

The photoluminescence (PL) of barite is a noncharacteristic property and cannot be used for the investigation of its structure. After thermal treatment of barite at 600°C several luminescent centers were observed, providing information about different impurities. UO 2 2+ was determined from the vibrational structure and the long decay time of the luminescence band. Two different types of uranyl were detected, thin films of uranyl mineral (most probably, reserfordin) and a solid solution of uranyl ion in barite crystal. Characteristic green luminescence of UO 2 2+ may be used as indicative feature for the prospecting of uranium deposits and for the sorting of barite ores with the aim of cleaning from harmful U impurities. Eu2+ was determined from the spectral position, the half-width and the characteristic decay time of the luminescence band. Mn2+ and Ag+ were determined by comparing luminescence bands spectral parameters to those of synthesized BaSO4−Mn and BaSO4−Ag. Fe3+ or Mn4+ were determined from the spectral-kinetic parameters of the luminescence bands.

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Abstract  

Luminescence lifetime of Eu(III) in polyacrylate and polymaleate complexes has been measured to evaluate the number of water molecules bound to the ion. The number of residual water molecules hydrated to Eu(III) in the polyacrylate and polymaleate complexes ranged from 3.5 to 4.5 when the supporting electrolyte concentration was 0.01. The residual hydration number decreased with the addition of supporting electrolyte. These results indicate that Eu(III) is surrounded by polymolecular ligands in these complexes.

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Abstract  

A method has been developed for the determination of microamounts of uranium in soils, which is based on application of the rapid and effective removing of luminescence quenchers from liquid preparations with subsequent uranium determination by laser-induced luminescence registration of its polysilicate complexes. To remove the luminescence quenchers, they were precipitated in strongly basic carbonate medium in the presence of activated charcoal (as a collector of the precipitate).

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, Jsrgensend , CK . Laser-induced luminescence of rare-earth elements in natural fluor-apatites . J Lumin . 1996 ; 69 : 343 – 353 . 10.1016/S0022-2313(96)00114-7 . 5. Mahabole , MP , Aiyer

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