SPECTROSCOPIC STUDY OF THE URANYL HYDROLYSIS SPECIES (UO2)(2)(OH)(2)(2+)

The behavior of (UO2)(2)(OH)(2)(2+) has been investigated in solid-liq uid equilibria under 100%, 8%, 1%, 0.3% and 0.03% CO2 partial pressure as well as in undersaturated systems in equilibrium with air at 24 +/ - 2 degrees C in 0.1M NaClO4 solutions. From spectroscopic investigati ons by UV-Vis-and time-resolved laser-induced fluorescence (TRLF) spec troscopies, single component absorption and emission spectra are sugge sted for the (UO2)(2)(OH)(2)(2+) Species. The lifetime tau(22) of the fluorescence emitting electronically excited state of. (UO2)(2)(OH)(2) (2+) was determined as tau(22)=2.9+/-0.9 mu s. The formation constant of (UO2)(2)(OH)(2)(2+) was found to be log K-22=-5.97 +/- 0.06. Interp retation of the experimental data was also made assuming the species ( UO2)(2)(OH)(4)(2+), but unsatisfactory results have been obtained.