Nonlinear Optical Spectroscopic Studies of Polymers and Liquid Crystals

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

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.