Anisotropic light absorption, refractive indices, and orientational order parameter of unidirectionally aligned columnar liquid crystal films.
Anisotropic light absorption, refractive indices, and orientational order parameter of unidirectionally aligned columnar liquid crystal films.
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单向排列柱状液晶膜的各向异性光吸收、折射率和取向顺序参数。
DOI：
10.1103/physreve.78.041707
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
E. Grelet
中科院分区：
文献类型：
--
作者：
Emilie Charlet;E. Grelet
本文研究了在开放支撑薄膜中，不同分散化合物单向取向的热致柱状液晶在可见光范围内的各向异性光学性质。两种方法来监测在薄膜中的柱状中间相的对齐报告，使得有可能通过特定的热退火，或通过使用摩擦聚四氟乙烯涂层的单向平面取向（列平行于基板），以实现垂直锚定（列垂直于基板）。发现柱状液晶锚定取决于化合物的性质，平行或垂直于Teflon取向。基于这种控制的中间相排列，二色性比和取向的样品的取向序参数进行了测量，并发现在平行排列的情况下的高阶参数为0.9。从柱状液晶膜的偏振吸收数据，确定在整个可见光范围内的双折射率和各向异性光学指数的真实的和虚部（折射率和消光系数，分别）的光的波长依赖性。
The anisotropic optical properties of thermotropic columnar liquid crystals absorbing in the visible range are investigated for different discotic compounds unidirectionally oriented in open supported thin films. Two methods to monitor the alignment of columnar mesophases in thin films are reported, making possible to achieve either homeotropic anchoring (columns normal to the substrate) by a specific thermal annealing, or unidirectional planar orientation (columns parallel to the substrate) by using a rubbed Teflon coating. The columnar liquid crystal anchoring is found to depend on the nature of the compound, either parallel or perpendicular to the Teflon orientation. Based on this control of the mesophase alignment, the dichroic ratio and the orientational order parameter of oriented samples are measured, and a high order parameter of 0.9 is found in the case of parallel alignment. From the polarized absorption data of the columnar liquid crystal films, the light wavelength dependence of the birefringence and of the real and imaginary parts (refractive index and extinction coefficient, respectively) of the anisotropic optical indices are determined over the whole visible range.