Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 f 0.006 ms, was observed from uranyl in 1 M HF + 1 M HC104 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to U02F2. Studies on the effect of added LiN03 or Na2W04'2Hz0 showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the u F 6 content of w F 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure w F 6 .

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