Infrared spectra of matrix-isolated uranium oxide species. I. The stretching region

Abstract

Stretching modes of several uranium oxide species vaporized from tungsten and iridium Knudsen cells and deposited in argon and krypton matrices have been observed in the 700–‐900 cm⁻¹ region of the infrared. Studies of the spectra as a function of temperature and composition of the condensed urania together with normal coordinate analyses of the spectra of ¹⁶O and ¹⁸O‐containing species have led to the following assignments for the ¹⁶O species in argon: ${\mathrm{U}}^{16}\mathrm{O}\text{(ν) = 820.0\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}\mathrm{;\hspace{0.17em}}{\mathrm{U}}^{16}{\mathrm{O}}_2{\mathrm{(\nu }}_3\text{) = 776.1\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}\mathrm{,\hspace{0.17em}}{\mathrm{U}}^{16}{\mathrm{O}}_2{\mathrm{(\nu }}_1\text{) = 765.4\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}\mathrm{\hspace{0.17em}(}\mathrm{calc})$ . The spectroscopic evidence strongly indicates a linear geometry for UO₂. Tentative assignments for the stretching modes of UO₃ are also given.