| Popis: |
The first-order Raman spectrum of La${\mathrm{Br}}_{3}$ is examined. All of the six Raman-active vibrations are observed and the ${C}_{6\mathbf{h}}$ point-group symmetry assignments for the lines are given: 83 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${E}_{2g}$; 116 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${A}_{g}$; 122 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${E}_{1g}$; 137.6 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${A}_{g}$; 139.2 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${E}_{2g}$; 146 ${\mathrm{cm}}^{\ensuremath{-}1}$, ${E}_{2g}$. The lines at 137.6 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 139.2 ${\mathrm{cm}}^{\ensuremath{-}1}$ are found to be resolvable at 77\ifmmode^\circ\else\textdegree\fi{}K but not at temperatures above 180\ifmmode^\circ\else\textdegree\fi{}K. The Raman spectrum of La${\mathrm{Br}}_{3}$ is compared with that of the isomorphic La${\mathrm{Cl}}_{3}$, which exhibits only five of the six Raman-active lines. |
