Nonlinear Optical Spectroscopic Studies of Polymers and Liquid Crystals

本计画主要针对三个主题：手性液晶材料的研究、与液晶排列相关的聚合物表面与界面的研究、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，手征性是指物体在平面镜中的图像与其自身不一致的结构不对称性。 手性液晶在液晶科学技术中的地位日益重要。 更一般地说，分子手性在科学和技术中也起着非常重要的作用，因为出于未知的原因，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学光谱技术，用于对这类特殊的液晶材料进行独特的研究。 该技术的高灵敏度允许测量不仅对散装流体，但也对单分子层，表面和薄膜的手性液晶。 从振动共振附近的光谱，手性分子的手性和手性强度在选定的原子团将推出。 它们将与手性分子结构和液晶体的宏观螺旋结构相关。 这一结果将有助于从分子水平上更好地理解手性，并为手性液晶的潜在应用奠定基础。液晶在现代世界中得到了广泛的应用，其表面性质通常是应用的决定因素。 这项研究将提高我们对液晶作为现代光电应用（如显示器、存储器和传感器器件）的非凡材料的认识。 液晶显示器中的基板和其他可能用于液晶配向的聚合物表面。 光谱技术也可以用来研究液晶单分子膜吸附在界面上。 关于液晶单层的取向和排列的信息是重要的，因为它们控制液晶膜的体取向。 更好地理解聚合物表面结构及其与吸附液晶单分子膜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.