Photo-orientation of liquid crystals due to light-induced desorption and adsorption of dye molecules on an aligning surface.
Photo-orientation of liquid crystals due to light-induced desorption and adsorption of dye molecules on an aligning surface.
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由于光诱导染料分子在对准表面上的解吸和吸附而导致液晶的光取向。
DOI：
10.1103/physreve.64.051709
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
F. Simoni
中科院分区：
文献类型：
--
作者：
E. Ouskova;Y. Reznikov;S. Shiyanovskii;L. Su;J. West;O. Kuksenok;O. Francescangeli;F. Simoni
我们发现，染料分子的吸附控制的光致取向的染料掺杂的非光敏聚合物表面的液晶（LC）。光致扭曲结构的曝光，热烘烤，厚度和老化的LC单元照射前的依赖关系，使我们能够提出以下机制的对齐。在照射之前，被测表面上的“暗”吸附层由主要沿指向矢的初始方向沿着排列的染料分子形成。用线性偏振光照射细胞产生具有染料分子的不同取向排序的附加层。最终的易轴由“暗”和光诱导的对锚定的贡献的竞争确定，并且在“暗”易轴和光的偏振之间对齐。对于定量解释，我们应用张量模型的锚定，并假设在中间相的光致取向是一个累积效应的光诱导锚定的背景上已经存在的各向异性的“暗”染料层。
We show that adsorption of dye molecules control the light-induced alignment of dye-doped nematic liquid crystal (LC) on a nonphotosensitive polymer surface. The dependencies of light-induced twist structures on exposure, thermal baking, thickness, and aging before irradiation of the LC cells allowed us to propose the following mechanism for the alignment. Before irradiation, the "dark"-adsorbed layer on the tested surface is formed from dye molecules predominantly aligned along the initial direction of the director. Irradiation of the cell with linearly polarized light produces an additional layer with different orientational ordering of dye molecules. The final easy axis is determined by the competition of "dark" and light-induced contributions to anchoring and is aligned between the "dark" easy axes and polarization of the light. For quantitative interpretation, we apply the tensor model of anchoring and assume that the photoalignment in the mesophase is a cumulative effect of the light-induced anchoring on the background of the already existing anisotropic "dark" dye layer.