# LASER RAMAN SPECTRA OF SOME CRYSTALLINE TRANSITION METAL HEXAFLUORIDES

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 Title: LASER RAMAN SPECTRA OF SOME CRYSTALLINE TRANSITION METAL HEXAFLUORIDES Creators: Meredith, G. R.; Bernstein, E. R. Issue Date: 1976 Publisher: Ohio State University Abstract: The Raman, effect of $MoF_{6}, WF_{6}, UF_{6}$ and $ReF_{6}$ in low temperature pure and mixed crystals has been investigated utilizing an Ar ion laser. Lowered crystal site symmetry has allowed the direct observation of the octahedral infrared and Raman forbidden $\nu_{6}(t_{2u})$ mode as well as the infrared allowed $\nu_{3}(t_{1u})$ and. $\nu_{4}(t_{1u})$ and Raman allowed $\nu_{1}(a_{1g})$, $\nu_{2}(e_{g})$ and $\nu_{5}(t_{2g})$ modes. Zero wavevector splittings were observed and both heavily doped and dilute mixed crystal techniques were used to elucidate the band structure and site effects. Identification of phonons as translational or librational based on the variation of molecular masses and near constancy of moments of inertia is complicated by mixing of these modes even at zero wavevector. Transitions corresponding to molecular combination and overtone vibrations were observed and interpreted in terms of single and two particle crystal states. The spectra of crystalline $ReF_{6}$ are complicated not only by a low lying electronic state $(\sim 25$ $cm^{-1})$ but also by exchange interactions particularly at helium temperatures The gas phase Raman spectrum of $ReF_{6}$ has previously been interpreted in terms of a Jahn-Teller effect in $\nu_{2}(e_{g})$ and $\nu_{5}(t_{2g})$ . Our data allow further comment on this effect. Description: Author Institution: Department of Chemistry, Colorado State University URI: http://hdl.handle.net/1811/9844 Other Identifiers: 1976-TD-5