Experimental Investigations of Thin Free-Standing Liquid Crystal Films

在这项研究中，独特的技术，差分交流自由， 静膜量热法用于测量 独立式液晶膜和其它液晶 中间相 该技术允许研究二维 物理现象，而没有复杂的影响，一个基板。 由于其极高的分辨率（优于1英寸）， 100，000），才有可能获得高质量的热容数据 从两层膜，并获取信息的意外 近晶-A-六方B附近的逐层转变序列 几种液晶化合物的转变。 此外，高- 分辨率光学反射率实验（优于5英寸 10，0000）与量热测量相结合， 热容和光学反射率的同时测量 各种液体薄膜和其他液晶中间相。 的 拟议的工作将使人们能够测试重要的理论 预测有关的Kosterlitz-numerless型转变， 两个维度，并将提供新的见解的物理 二维无基质系统。 %%% 本文介绍了一种新型的差示交流热量计。 研究是用来测量热容量的独立 液晶膜（类似于环上的肥皂膜）薄至 两个分子层 这种独特的技术提供了新的 有机会研究几个关键的二维 物理现象，而没有复杂的影响，一个基板。

In this research, the unique technique of differential ac free- standing film calorimetry is used to measure the heat capacity of free-standing liquid crystal films and other liquid crystal mesophases. This technique allows investigation of two-dimensional physical phenomena without the complicating effects of a substrate. Because of its extremely high resolution (better than 1 in 100,000), it is possible to obtain high-quality heat capacity data from the two-layer films, and acquire information on unexpected layer-by-layer transition sequence near the smectic-A-hexatic B transition of several liquid crystal compounds. In addition, high- resolution optical reflectivity experiments (better than 5 in 10,0000) are coupled to the calorimetric measurements to allow simultaneous measurements of heat capacity and optical reflectivity of various liquid films and other liquid crystal mesophases. The proposed work will enable one to test important theoretical predictions related to the Kosterlitz-Thouless-type transition in two dimensions, and will provide new insights into the physics of two-dimensional substrate-free systems. %%% A state of art differential ac calorimeter developed in this research is used to measure the heat capacity of free-standing liquid crystal films (similar to soap films on a ring) as thin as two molecular layers. This unique technique offers new opportunities to investigate several critical two-dimensional physical phenomena without the complicating effects of a substrate.