Polarized infrared absorption spectrum of Cs2UO2Cl4

Abstract

Polarized infrared spectra have been measured on single crystals of Cs₂UO₂Cl₄ at room and liquid-nitrogen temperatures. All features between 2000 and 400 cm^–1 are assigned to (a) fundamental modes of ¹⁶OU¹⁶OCl^2–₄, ¹⁷OU¹⁶OCl^2–₄ and ¹⁸OU¹⁶OCl^2–₄ ions, (b) combination bands involving two internal anion modes and (c) vibron–phonon modes involving one internal mode and one lattice mode. The structure of the features (c) reflects the dispersion of the lattice modes. These data, together with new Raman spectra, enable assignments of all the internal modes of the UO₂Cl^2–₄ ion to be proposed.