A Raman spectroscopic study of the uranyl phosphate mineral threadgoldite

Abstract

Raman spectra of threadgoldite at 298 and 77K are measured and interpreted for the first time. Bands related the (UO2)2+ and (PO4)3− stretching and bending vibrations are tenatively attributed together with the bands assigned to the stretching a and bending vibrations of water molecules and hydroxyls. Hydrogen-bonding network and H2O and (OH)−1 libration modes are mentioned. U–O bond lengths in uranyls are calculated via empirical relations RU–O=f[ν1 and ν3(UO2)2+]Å. They are comparable to the values inferred from the single crystal structure analysis of threadgoldite.