Coherent Anti-Stokes Raman Scattering and Fluorescence Confocal Polarizing Microscopy of Three-Dimensional Structures in Liquid crystals

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”技术概述：液晶是许多现代技术的关键材料。正如诺贝尔奖得主P.G.德热内斯所说：“……液晶的研究很复杂，因为它涉及到……一定的视觉在三维空间，以可视化复杂的分子排列”。直到最近，为了证实这种视觉…在美国，研究人员和教育工作者依赖于间接信息，比如综合二维图像。该项目将扩展最近开发的液晶分子取向三维可视化技术，即所谓的荧光共聚焦偏振显微镜（FCPM）和相干反斯托克斯拉曼散射显微镜（CARS），以研究液晶中复杂的三维结构，包括静态和动态。CARS的一个独特特征，即无标记化学敏感性，将用于确定具有潜在双轴取向顺序的化合物的化学键的取向。FCPM将用于探索液晶介质中胶体颗粒的动力学。由于颗粒表面的有限锚定，系统中引入了定向变形，它强烈影响颗粒的动力学，使其与常规流体中的动力学完全不同。这个问题非常复杂，只能通过这个项目将提供的3D可视化工具来访问。这项研究将在肯特州立大学液晶研究所进行，该研究所提供完善的研究生和本科生培训机制（由美国国家科学基金会本科生研究经验资助），并为工业伙伴关系提供肥沃的土壤（工业伙伴关系计划，约有30家公司会员）。所获得的知识将有助于其他对社会有潜在实际效益的项目，即开发快速开关显示器和基于液晶的光学和微流体器件。非技术概述：液晶结合了晶体和液体的特性。它们表现出与常规固体晶体相似的光学特性，但与此同时，它们对即使是最弱的外部因素也非常敏感，比如小电压脉冲。它解释了为什么液晶是被普遍称为“lcd”（液晶显示器）的关键材料。正如该领域的诺贝尔奖得主P.G.德热内斯所说：“……液晶的研究很复杂，因为它涉及到……一定的视觉在三维空间，以可视化复杂的分子排列”。最近，俄亥俄州肯特州立大学液晶研究所的研究人员开发了一种特殊的显微镜技术，可以获得液晶中复杂分子排列的真正三维图像。研究人员将使用这些仪器来研究液晶中以前根本无法研究的新的有希望的现象。其中一个主题是寻找所谓的双轴向列，它有望显著提高lcd的开关速度。第二个主题是探索在液晶环境中控制小粒子运动的原理。这里的目标是了解液晶的独特性质是否可以用来推动粒子，从而创造一个胶体微电机。这项研究将在肯特州立大学液晶研究所进行，该研究所将研究生和本科生培训与工业合作计划相结合。所获得的知识将有助于开发快速开关lcd，微流体和光学器件。液晶的三维可视化有助于研究生和本科生掌握现代先进材料科学的精髓。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."TECHNICAL SUMMARY:Liquid crystals are the key material in many modern technologies. As stated by the Nobel Prize winner P.G. de Gennes, ''...the study of liquid crystals is complicated because it involves...a certain sense of vision in three-dimensional space in order to visualize complex molecular arrangements''. Until recently, to substantiate this sense of vision..., researchers and educators relied on indirect information, such as integrated 2D images. This project will expand the recently developed techniques of 3D visualization of the molecular orientation in liquid crystals, the so-called Fluorescence Confocal Polarizing Microscopy (FCPM) and Coherent Anti-Stokes Raman Scattering (CARS) microscopy, to the studies of complex three-dimensional structures in liquid crystals, both static and dynamic. A unique feature of CARS, namely, label-free chemical sensitivity, will be used to establish orientation of chemical bonds in compounds with potentially biaxial orientational order. FCPM will be used to explore the dynamics of colloidal particles in the liquid crystal medium. Director distortions, introduced in the system by finite surface anchoring at the particle surface, strongly affect the dynamics of particle, making it radically different from the dynamics in regular fluids. The problem is very complex and can be accessed only with a 3D visualization tool that this project will provide. This research will be conducted at the Liquid Crystal Institute at Kent State University which offers well established mechanisms for graduate and undergraduate training (supported by NSF Research Experience for Undergraduates grant), and a fertile ground for industrial partnership (Industrial Partnership Program with about 30 companies membership). The acquired knowledge would help in other projects with the potential practical benefits to society, namely, in the development of fast switching displays and liquid crystal-based optical and microfluidic devices.NON-TECHNICAL SUMMARY:Liquid crystals combine properties of both crystals and liquids. They show optical properties similar to that of regular solid crystals but at the very same time they are very sensitive to even the weakest external factors, such as a small voltage pulse. It explains why the liquid crystals are a key material in what is universally known as "LCDs", liquid crystal displays. As stated by the Nobel Prize winner in the field, P.G. de Gennes, ''...the study of liquid crystals is complicated because it involves...a certain sense of vision in three-dimensional space in order to visualize complex molecular arrangements''. Recently, researchers at the Liquid Crystal Institute, Kent State University, Ohio, have developed special microscopy techniques to obtain truly three-dimensional images of the complex molecular arrangements in liquid crystals. The researchers will employ these instruments to look into the new promising phenomena in liquid crystals that simply could not be studied before. One theme is a search for the so-called biaxial nematic that promises to dramatically improve the switching speed of LCDs. The second theme is to explore principles that control a motion of a small particle in a liquid crystal environment. The goal here is to learn whether the unique properties of the liquid crystal can be used to propel the particles and thus create a colloidal micromotor. This research will be conducted at the Liquid Crystal Institute at Kent State University that combines graduate and undergraduate training with industrial partnership program. The acquired knowledge would help in the development of fast switching LCDs, microfluidic and optical devices. Three-dimensional visualization of liquid crystals would help both graduate and undergraduate students to grasp the essence of modern science of advanced materials.