A Raman spectroscopy study of hydroxo and carbonato species of the uranyl (VI) ion

Abstract The Raman spectra of a number of uranyl species in carbonate and alkaline solutions have been obtained as well as those of solids obtained from carbonate media. The frequency of the UO2−ν1 symmetric stretching vibration of these species can be used to complement evidence derived by other means in their identification. Thus, the existence of uranyl hemicarbonate, (UO2)2CO3(OH)3−, has been demonstrated as well as that of anionic hydroxo species, such as UO2(OH)42−. The conversion of UO2(CO)32− into UO2(CO3)34− by addition of HCO3− was followed by Raman spectroscopy and 13C NMR. Solid solutions with compositions within that of UO2CO3 and sodium uranate have been detected. A correlation was observed between the ν1 frequency and the number and nature of the ligands surrounding the uranyl ion.