Dynamical and Structural Studies of Liquid Crystal Phases

本研究的目的是利用光学显微镜、光和X射线散射以及扫描隧道显微镜来研究液晶相的结构和动力学行为。要探索的系统包括平面自由悬浮液晶膜、固体基质之间的超薄制备、限制在气凝胶基质中的液晶以及液晶-固体界面。这项研究旨在阐明表面和降维对液晶涨落、有序和相变的影响。拟议中的研究之所以重要，是因为它们对凝聚态物理产生了根本性的影响，也因为技术上的兴趣。%这项研究主要集中在自由悬浮液晶膜、固体衬底之间的超薄制备、多孔介质中的液晶以及吸附液晶层的扫描隧道显微镜。这项研究旨在阐明表面和降维对液晶涨落、有序和相变的影响。自由悬浮液晶膜是凝聚态物理中最有意义的结构，因为它们是已知的最薄、最稳定的凝聚态结构，并且在任何凝聚态制备中具有最大的表面积/体积比。液晶的弱有序性和强界面相互作用使其成为研究多孔介质中凝聚相变物理的理想材料。这一领域是过去二十年来液晶研究的一个令人兴奋的延伸。固体衬底之间的超薄液晶薄膜不仅引起了广泛的技术兴趣，而且继续产生了各种有趣的基本物理问题。

The goal of this research is to study the structure and dynamical behavior of liquid crystal phases using optical microscopy, light and x-ray scattering, and scanning tunneling microscopy. Systems to be probed include planar freely suspended liquid crystal films, ultrathin preparations between solid substrates, liquid crystals confined to an aerogel matrix, and liquid crystal-solid interface. The research is directed toward elucidating the effects of surfaces and reduced dimensionality on liquid crystal fluctuations, ordering and phase transitions. The proposed studies are important because of their fundamental impact on condensed matter physics and due to technological interests. %%% This research is focused on freely suspended liquid crystal films, ultrathin preparations between solid substrates, liquid crystals in porous media, and scanning tunneling microscopy of adsorbed liquid crystal layers. The research is directed toward elucidating the effects of surfaces and reduced dimensionality on liquid crystal fluctuations, ordering and phase transitions. Freely suspended liquid crystal films are structures of fundamental interest in condensed matter physics because they are the thinnest known stable condensed phase structures and have the largest surface-to-volume ratio of any condensed phase preparation. The weak ordering and strong interface interactions of liquid crystals makes them ideal materials for studying the physics of condensed phase transition in porous media. This area is emerging as an exciting extension of liquid crystal phase research of the past two decades. Ultrathin liquid crystal films between solid substrates are not only of broad technological interest but they continue to generate a variety of interesting basic physics problems.