Pretransitional Behavior in the Isotropic Phase of Homologous Compounds Showing Nematic and Smectic C Type Order
We report here the preliminary results of our study of pre-transitional behavior in the isotropic phase of three homologous compounds showing smectic C type order. We have measured the intensity and spectrum of scattered light in the isotropic phase of dialkoxyazoxybenzenes with terminal octyl (C8H17), decyl (C10H21), and undecyl (C11H23) groups1. All three compounds have a smectic C phase. The octyl and decyl compounds also have nematic phases over a range of 18°K and 2°K, respectively. The undecyl compound has a direct smectic C-isotropic transition. Previous light scattering experiments in liquid crystals just above the nematic-isotropic2 and the cholesteric-isotropic3 transitions have shown the existence of pretransitional phenomena in the isotropic phase. Both the static and dynamic behavior are in good agreement with de Gennes’ phenomenological theory of short-range orientational orders4. The purpose of our experiment is to investigate the effect of nearby smectic order on the fluctuations in the orientational order in the isotropic phase.
KeywordsLiquid Crystal Nematic Phasis Isotropic Phase Type Order Orientational Order
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