Spectroscopic study of the uranyl hydrolysis species (UO2)2(OH)22+

The behavior of (UO2)2(OH)22+ has been investigated in solid-liquid equilibria under 100%, 8%, 1%, 0.3% and 0.03% CO2 partial pressure as well as in undersaturated systems in equilibrium with air at laser-induced fluorescence (TRLF) spectroscopies, single component absorption and emission spectra are suggested for the (UO2)2(OH)22+ species. The lifetime τ22 of the fluorescence emitting electronically excited state of (UO2)2(OH)22+ was determined as τ22=2.9±0.9 μs. The formation constant of (UO2)2(OH)22+ was found to be log K22=-5.97±0.06. Interpretation of the experimental data was also made assuming the species (UO2)2(OH)42+, but unsatisfactory results have been obtained. (author) 28 refs.; 8 figs.; 4 tabs