Chemiluminescence in the solid-phase reaction of powdered XeF2 and Na4XeO6 · nH2O with U(OH) 4 · nH2O

Reactions of solid-phase oxidation of U(OH)4 · nH 2O with Xe compounds to U(VI), accompanied by intense chemiluminescence, were revealed and examined. The reactions are typically complete within ∼60 min at 20°C, i.e., are much faster than oxidation of crystalline U(IV) salts, e.g., U(SO4)2 · nH 2O. The reactions of U(OH)4 · nH2O with XeF2 and Na4XeO6 · nH2O substantially differ in the chemiluminescence kinetics: In the former case, there is a chemiluminescence intensity splash, followed by a smooth decay, while in the latter case the luminescence flames up from the initial moment after mixing and passes through one, and then through another, maximum. A complex kinetics of both reactions can be due, in particular, to successive oxidation of U(IV) to U(VI) via formation of intermediate U(V) and Xe(I) species. The chemiluminescence spectrum of U(OH)4 · nH2O is observed in the 440-580 nm range and falls within the UO 2 2+ ion emission region. Despite the differences in the chemiluminescence spectra of the solid compound and UO 22+ aqua ion, hydroxo complexes of U(VI), formed from oxidation of U(IV), were identified as chemiluminescence emitters. In the discovered solid-phase chemiluminescence reactions, an important role is played by water of crystallization and coordinated water. © 2007 Pleiades Publishing, Inc.