Polarized infrared absorption spectrum of Cs2UO2Cl4

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 16OU16OCl42-, 17OU16OCl42- and 18OU16OCl42- 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 UO2Cl42- ion to be proposed. (author)