The incoherent quasi-elastic neutron scattering from the heptyl and octyl derivatives of the acta-alkylphthalocyanines, CnPcH(2), in their crystalline and liquid crystalline (discotic columnar) phases has been measured. Diffusive motion is observed on the 10^-10 to 10^-12 s timescale. This is interpreted as alkyl chain motion. A. detailed comparison of the mesophase data for C7PcH(2) has been made with the predictions of the rotational isomeric state model, and an extra motion on this timescale has been invoked, which probably is a localized translational motion. A small discontinuity in the elastic fraction of the quasi-elastic scattering is consistent with a change in the molecular tilt at the transition between the two Dhd phases.
A quasi-elastic neutron scattering study of molecular dynamics in a columnar liquid crystal
FREZZATO, DIEGO;FERRARINI, ALBERTA;NORDIO, PIER LUIGI;
1998
Abstract
The incoherent quasi-elastic neutron scattering from the heptyl and octyl derivatives of the acta-alkylphthalocyanines, CnPcH(2), in their crystalline and liquid crystalline (discotic columnar) phases has been measured. Diffusive motion is observed on the 10^-10 to 10^-12 s timescale. This is interpreted as alkyl chain motion. A. detailed comparison of the mesophase data for C7PcH(2) has been made with the predictions of the rotational isomeric state model, and an extra motion on this timescale has been invoked, which probably is a localized translational motion. A small discontinuity in the elastic fraction of the quasi-elastic scattering is consistent with a change in the molecular tilt at the transition between the two Dhd phases.
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