Nonlinear Optical Spectroscopic Studies of Polymers and Liquid Crystals

本项目主要研究三个主题：手性液晶材料的研究，与液晶排列相关的聚合物表面和界面的研究，以及液晶显示器中液晶体排列的表面效应研究。根据开尔文勋爵的说法，手性是指物体在平面镜中的像与自身不重合的结构不对称性。手性液晶在液晶科学技术中占有越来越重要的地位。更一般地说，分子手性在科学技术中也起着异常重要的作用，因为由于未知的原因，几乎所有的天然产物，如DNA和蛋白质都是手性的。研究将包括开发非线性光谱学技术，用于这类特殊液晶材料的独特研究。该技术的高灵敏度不仅可以测量大体积流体，还可以测量手性液晶的单层、表面和薄膜。从振动共振附近的光谱，可以推导出手性分子中选定原子群的手性和手性强度。它们将与液晶体的手性分子结构和宏观螺旋结构相关。该结果将从分子水平上更好地理解手性和手性液晶的性质，为潜在的应用提供帮助。液晶在现代世界中有广泛的应用，其表面特性往往是决定应用的因素。这项研究将增强我们对液晶作为现代光电应用的非凡材料的认识，如显示器、存储器和传感器设备。液晶显示器中的衬底和其他聚合物表面可能对液晶排列有用。光谱学技术也可用于研究在界面上吸附的液晶单层。液晶单层的取向和排列信息是重要的，因为它们控制着液晶膜的整体排列。更好地了解聚合物表面结构及其与吸附液晶单层的相互作用将有助于未来液晶器件的设计。

This project focuses on three topics: studies of chiral liquid crystalline materials, studies of polymer surfaces and interfaces relevant to liquid crystal alignment, and studies of surface effects on liquid crystal bulk alignment for liquid crystal displays. According to Lord Kelvin, chirality refers to the structural asymmetry of an object whose image in a plane mirror does not coincide with itself. Chiral liquid crystals have become increasingly important to liquid crystal science and technology. More generally, molecular chirality also plays an exceptionally important role in science and technology in science because, for reasons unknown, practically all natural products such as DNA and proteins are chiral. Research will include developing the nonlinear optical spectroscopic technique for unique studies of this special class of liquid crystalline materials. High sensitivity of the technique allows measurements not only on the bulk fluid but also on monolayers, surfaces, and films of chiral liquid crystals. From the spectra near vibrational resonances, chirality and chiral strength in selected atomic groups of chiral molecules will be deduced. They will be correlated to the chiral molecular structure and the macroscopic helical structure of the liquid crystal bulk. The results will yield a better understanding of chirality from the molecular level and chiral liquid crystal properties for potential applications.%%%Liquid crystals have found wide applications in the modern world, with the surface properties often being the determining factors for an application. This research will enhance our knowledge of liquid crystals as extraordinary materials for modern optoelectronic application such as displays and memory and sensor devices. Substrates in liquid crystal displays and other polymer surfaces potentially useful for liquid crystal alignment. The spectroscopic technique also can be used to study liquid crystal monolayers adsorbed at an interface. Information on the orientation and alignment of liquid crystal monolayers is important as they control the bulk alignment of liquid crystal films. A better understanding of the polymer surface structures and their interaction with adsorbed liquid crystal monolayers would be of help to the design of future liquid crystal devices.