Investigation of radioluminescence of curium(3) in solutions

Curium (3) radioluminescence under the effect of intrinsic α-radiation in aqueous, heavy water and organic solutions is studied. The luminescence maximum is at λ≅ 600 nm. Radioluminescence yield G is proportional to the concentration (or electron part) of curium and for 10-2 mol/l aqueous solution of Cm(NO3)3 G≅ 5x10-4 quanta per 100 eV of absorbed energy. In diluted acids radioluminescence yield is the same as in neutral solution, but in concentrated acids it is varied significantly. In the presence of ligands (formate-, acetate-, citrate-ions, etc.) radio luminescence yield of curium in aqueous solutions increases, which is related to complexing, leading to the decrease of excited curium quenching by water molecules. Curium radioluminescence increase in the presence of sodiumparatungstate is especially high; it is assumed that in this case energy transfer from ligand to curium plays a very considerable role. H2O2, NH2NH2, NH2OH, Ce(4) and ions of uranium, neptunium and plutonium in different oxidation states do not affect curium radioluminescence in any significant way. Somewhat greater quenching of the radioluminescence by NpO2+ ions than by other actinide ions is associated with the formation of cation-cation complexes of NpO2+ with Cm3+. In heavy water and organic solutions a strong increase in curium radioluminescence yield is observed, which is in a good agreement with data on photoluminescence. The results obtained permit to make the assumption that curium luminescence in solutions (in the absence of ligands-energy donors) is mainly excited in the direct way, and the role of energy transfer on curium from solvent or products of its radiolysis is investigated