The FTIR study of uranium oxides by the method of light pipe reflection spectroscopy

Abstract

Light pipe infrared reflection spectra of UO₂, UO₃, U₃O₈ have been studied by using an FTIR spectrometer. The uranium oxide powders were ground to ensure fine particle size and distributed on the inner surface of a straight glass pipe with gold coating. The infrared beam from the interferometer was focused into one end of the pipe at 45° incidence and then the transmitted beam was refocused by a pair of Cassegrainian type mirrors. The resultant spectra show the infrared characteristics of the ⋯-U-O-U-O-⋯, uranyl ion UO ²⁺₂ bond vibration and the active lattice vibrations predicted by group theory calculations. In comparison to the transmission spectra measured by authors or reported in literature, this 45° incident light pipe method as well as the previous light pipe method offer advantages of sensitivity, ease of acquisition and interpretation, and require a very small sample. It confirms the power of the light pipe method for studying powders and its special utility for the infrared studies of hazardous materials.