Evidence for de Vries structure in a smectic-A liquid crystal observed by polarized Raman scattering.
Evidence for de Vries structure in a smectic-A liquid crystal observed by polarized Raman scattering.
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通过偏振拉曼散射观察到的近晶 A 液晶中德弗里斯结构的证据。
DOI：
10.1103/physreve.71.041705
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
S. Kondoh
中科院分区：
文献类型：
--
作者：
N. Hayashi;Tatsuhisa Kato;A. Fukuda;J. Vij;Y. Panarin;J. Naciri;R. Shashidhar;Sachiko Kawada;S. Kondoh
用偏振振动拉曼光谱测量了非手性末端链上含有三个二甲基硅氧烷基团的均匀排列的铁电近晶相液晶的分子P2（app）和P4（app）的核部分的二阶和四阶表观取向序参数，显示出de Vries型现象，即，在近晶- A（Sm-A）相中具有非常大的电斜效应，而在Sm-A和Sm-C（*）相之间的相变处具有可忽略的层收缩。在Sm-A中，无论有无外加电场，分子刚性核部分的表观取向序参数都非常小。这些结果为de弗里斯Sm-A相的存在提供了证据，其中局部分子指向矢以大角度倾斜。
The second- and fourth-order apparent orientational order parameters of the core part of the molecule P2 (app) and P4 (app) , have been measured by polarized vibrational Raman spectroscopy for a homogeneously aligned ferroelectric smectic liquid crystal with three dimethyl siloxane groups in the achiral terminal chain, which shows de Vries-type phenomena, i.e., very large electroclinic effect in the smectic- A (Sm-A) phase and a negligible layer contraction at the phase transition between the Sm-A and Sm- C(*) phases. The apparent orientational order parameters of the rigid core part of the molecule are extremely small both with and without the external electric field in Sm-A . These results provide evidence for the existence of the de Vries Sm-A phase, where the local molecular director is tilted at a large angle.