Luminescence of uranyl monofluoride complex in solution

Uranyl ions photoluminescence spectra as a result of fluoride-ions concentration variation up to 3x10-4 mol/l in 0.1 mol/l HClO4 solution at the temperature t=25 deg C are recorded. Complexing by the reaction (UO2aqua2++F- ↔ (UO2F+)) leads to the shift of maxima and broadening of luminescence spectra bands in solution. It is shown that due to the ''slow'' ligand exchange, when deactivated rate of electron-excited states exceeds the rates of ligand exchange between (UO22+)aqua and (UO2F+), ultimate spectrum of stationary luminescence of uranyl ion solution in the presence of fluorine-ions can be unfolded into constituents, corresponding to spectra of individual complexes. Luminescence spectrum of uranyl monofluoride complex in solution is obtained. It is found that the obtained luminescence spectrum of (UO2F+) does not change with fluoride-ions concentration variation from 1 to 3x10-4 mol/l. It is shown that in the range of solution composition studied at low intensity of exciting light the presence of uranyl electron-excited ions does not affect the ratio of concentrations of aqua- and monofluoride complexes of UO22+ in solution. Therefore, concentrations of the latter, when unfolding the spectra into constituents, were calculated by the known stability constants of uranyl monofluoride complex in the basic state