Spectroscopic studies of the several isomers of UO3

Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO 3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO 3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO 3 . Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO 3 , β-UO 3 , γ-UO 3 and α-UO 2 (OH) 2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO 3 , which are often mixtures of isomers.