Lattice Vibrations in Chlorobenzenes: Experimental Dispersion Curves for beta-Paradichlorobenzenes by Neutron Scattering

P. A. Reynolds, Jørgen Kjems, J. W. White

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    Abstract

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K was applied in order to correct for anharmonic effects. Calculations based on the atom‐atom model for van der Waals' interaction and on general potential parameters for the aromatic compounds agree reasonably well with the experimental observations. There is no substantial improvement in fit obtained either by consideration of electrostatic forces or by further anisotropy in the dispersion forces not described in the atom‐atom model. Anharmonic effects are shown to be large, but the dominant features in the temperature variation of frequencies are describable by a quasiharmonic model.
    Original languageEnglish
    JournalJournal of Chemical Physics
    Volume60
    Issue number3
    Pages (from-to)824-834
    ISSN0021-9606
    DOIs
    Publication statusPublished - 1974

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