Lifetime and fluorescence quantum yield of uranium(VI) species in hydrolyzed solutions

Abstract

Fluorescence lifetimes and emission intensities of uranium(VI) species UO22+, (UO2)2(OH)22+ and (UO2)3O(OH)3+ (=(UO2)3(OH)5+) are determined after excitation by a dye laser at 420 nm. Despite the widely varying species concentrations in the different solutions, single-exponential decay with emission lifetimes between 2 μs and 15.5 μs has been observed, continuously varying with solution composition. Solution composition has been assessed by interpreting UV–Vis absorption spectra in the range 340 nm to 580 nm by available single component spectra. Factor analysis is used to assess the number of absorbing species in solution. Relative fluorescence quantum yields 12±3 and 10±3 times higher than for UO22+ have been found for the (UO2)2(OH)22+ and (UO2)3O(OH)3+ species.