Rotational diffusion in para-azoxyanisole
- 1 January 1972
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Faraday Symposia of the Chemical Society
- Vol. 6, 48-56
- https://doi.org/10.1039/fs9720600048
Abstract
Dielectric susceptibility (ε′, ε″) measurements were made on isotropic, nematic, and solid para-azoxyanisole in the micro-wave region. From the Cole-Cole plots, dielectric relaxation times were determined and the barrier-to-rotation, interpreted as corresponding to rotation around the long molecular axis, was estimated to be 2.6 kcal/mol in the isotropic phase and 2.3 kcal/mol in the nematic phase. In the solid phase ε′ drops to low values practically equal to ε∞. Infra-red measurements were performed additionally for the solid substance. From the temperature dependence of the peak widths at 910 cm–1(benzene rings), 1020 cm–1(O—CH3 groups), and 1330 cm–1(N2O group) the corresponding barriers-to-rotation were found to be 1.9, 1.9 and 4.5 kcal/mol respectively. The possible influence on neutron quasielastic scattering measurements is discussed.Keywords
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