The Far-IR Spectra of UO ₂ , α-U ₃ O ₈ , and γ-UO ₃ Using the Light Pipe Reflection Method

The spectra of UO 2 , α-U 3 O 8 , and γ-UO 3 in the 700–20 cm −1 range were examined with an FT-IR spectrometer with the use of a Cassegrainian-type light pipe cell. Generally, the light pipe reflection spectra obtained show more detail than the transmission measurements. Some weak peaks of lattice mode vibrations have been found. The coincidence of several spectral features in α-U 3 O 8 and UO 2 provides evidence that their structures are correlative. The spectra of γ-UO 3 in this region are the first reported.