Infrared spectra of matrix-isolated plutonium oxides

Abstract

The infrared absorption spectra of PuO and PuO₂ in both Ar and Kr matrices have been identified. The observed frequencies at 794.25 and 786.80 cm⁻¹ have been assigned to the ν₃ stretching modes of Pu¹⁶O₂ in Ar and Kr matrices, respectively. Normal coordinate analysis of the PuO₂ isotopomers, Pu¹⁶O₂, Pu¹⁶O¹⁸O, and Pu¹⁸O₂, in Ar showed that the molecule is linear. The derived stretching force constants are f=5.2476±0.0010 and f ′=0.0034±0.0010 mdyn Å⁻¹. The PuO molecule exists in multiple sites in Ar matrices, but not in Kr matrices. The observed Pu¹⁶O vibrational frequency in the most stable site in Ar is 822.28 cm⁻¹ and in Kr is 817.27 cm⁻¹. No absorption peaks were observed that could be assigned to PuO₃.