Coupling between molecular vibrations and liquid crystalline order parameters.
Specific Raman active modes in two prototype cyanobiphenyl liquid crystals are shown to display a temperature dependent softening proportional to either the nematic or smectic order parameters, while other vibrations (like the C identical withN stretch mode) remain unaltered. This selective coupling between intramolecular vibrations and the liquid crystalline order is related to the intrinsic symmetry of the modes. The method provides a simple, microscopic, noninvasive optical technique with which the liquid crystalline order parameters can be qualitatively mapped out.
Nöllmann
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Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, 8400-San Carlos de Bariloche, Río Negro, Argentina.
Etchegoin
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