Fluorescence properties of a uranyl(V)-carbonate species [U(V)O(2)(CO(3))(3)](5-) at low temperature.

Fluorescence properties of a uranyl(V)-carbonate species in solution are reported for the first time. The fluorescence characteristics of the stable aqueous uranyl(V)-carbonate complex [U(V)O(2)(CO(3))(3)](5-) was determined in a frozen solution (T=153K) of 0.5mM uranium and 1.5M Na(2)CO(3) at pH 11.8 by time resolved laser-induced fluorescence spectroscopy (TRLFS). Two different wavelengths of 255nm and 408nm, respectively were used to independently of each other excite the uranyl(V)-carbonate species. The resulting U(V) fluorescence emission bands were detected between 380nm and 440nm, with a maxima at 404.7nm (excitation with 255nm) and 413.3nm (excitation with 408nm), respectively. It was found that by using an excitation wavelength of 255nm the corresponding extinction coefficient was much higher and the fluorescence spectrum better structured than the ones excited at 408nm. The fluorescence lifetime of the uranyl(V)-carbonate species was determined at 153K as 120micros. TRLFS investigations at room temperature, however, showed no fluorescence signal at all.