Search for plutonium fluorescence

The possible fluorescence of aqueous Pu in its various oxidation states at room temperature was investigated, over the wavelength range of 300 to 800 nm. For each oxidation state, absorption spectral measurements were made of the experimental solutions, both before and after fluorometric study, to confirm that the desired oxidation state of Pu was studied. No emissions were observed for aqueous solutions of plutonium in any of its oxidation states of (III), (IV), (V), (VI) or (VII). A reaction of thenoyltrifluoroacetone (TTA) with Pu(VI) was found to yield a fluorescent, organic product which might serve as a basis for a fluorometric determination of Pu(VI). In a slightly basic solution, pH 7 to 8, Pu(VI) will oxidize TTA within a matter of seconds to yield a product that exhibits an emission peak at 550 nm with a shoulder at 500 nm. It was demonstrated that Pu(VI) is reduced to Pu(IV) in the reaction with TTA. The method is suited to the fluorometric determination of Pu(VI) even in the presence of Pu(IV), and with the incorporation of photon counting techniques, the determination could be quite sensitive. (U.S.)