BRILLOUIN SCATTERING IN MOLECULAR CRYSTALS: s-TRICHLOROBENZENE

Author Institution: Department of Chemistryq, University of Southern California; INSA, University of Southern CaliforniaBrillouin scattering can yield information concerning the anisotropic acoustic vibrations of a crystal lattice. These acoustic frequencies are related to other physical properties of the crystals such as the elastic constants, and may provide extensive information concerning intermolecular forces. We have obtained the Brillouin scattering spectrum of single crystal samples of s-trichlorobenzene as a function of scattering angle for nine directions of propagation in the orthorhombic axis system. Sound velocities and elastic constants are derived. The experimental results are compared with values calculated using atom-atom intermolecular potentials with parameters derived from other data on a number of chlorobenzene crystals. The above results have been taken, in part, from a dissertation (D.L.S.), and reported in preliminary form in Chem. Phys. Letters 23, 430 (1973). Present address of Douglas L. Swanson: Department of Chemistry, University of Minnesota, Minneapolis, Minnesota. Present address of L. -C. Brunel: INSA, Lyon, France