Laser Induced Kerr effect spectroscopy

激光诱导克尔效应光谱

基本信息

批准号：
09450035
负责人：
SAKAI Keiji
金额：
$ 8.32万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Complex fluids such as gels, emulsions and bio-systems attract a great physical interest since they could be applied for various industries as new functional materials. The characteristic properties of the complex fluids can be attributed to their large degree of freedom, such as molecular conformation and association. The molecular orientation is one of the important orders, which plays a significant role in creating the liquid crystal phase. The purpose of the study is to develop a new experimental system for observing the orientational molecular dynamics of liquid materials in a wide frequency range.We successfully developed the optical Kerr effect spectroscopy technique with a continuous wave laser. The anisotropic shape of the molecule necessarily accompanies the anistropic dielectricity. The electric field of the polarized laser beam induces the molecular orientation, which is measured by the optical ellipsometry as the Kerr effect. The critical phenomenon was observed for the nematogen near the nematic-isotropic phase transition temperature. The system was improved to observe the dynamic process of molecule rotation. The Pockels cell was driven with a wide band power supply for the high frequency control of the laser polarization. The complex response function was accurately measured, which gives us an important information on the phase transition and the molecular dynamics of liquid crystals. We observed the relaxation of the optical Kerr effect for the first time in the frequency domain in various kinds of liquid crystals. The laser induced molecular orientation technique would be a powerful tool for the investigation of the mechanism of phase transition of liquid crystals.

凝胶、乳液和生物系统等复杂流体引起了人们极大的兴趣，因为它们可以作为新的功能材料应用于各个行业。复杂流体的特性可归因于其较大的自由度，例如分子构象和缔合。分子取向是重要的顺序之一，在液晶相的形成中起着重要作用。该研究的目的是开发一种新的实验系统，用于在宽频率范围内观察液体材料的取向分子动力学。我们成功开发了连续波激光器的光学克尔效应光谱技术。分子的各向异性形状必然伴随着各向异性介电性。偏振激光束的电场引起分子取向，这是通过光学椭圆光度法测量的克尔效应。在向列相-各向同性相变温度附近观察到线母的临界现象。改进系统以观察分子旋转的动态过程。普克尔斯盒由宽带电源驱动，用于激光偏振的高频控制。精确测量了复杂的响应函数，这为我们提供了有关液晶相变和分子动力学的重要信息。我们首次在各种液晶的频域中观察到光学克尔效应的弛豫。激光诱导分子取向技术将成为研究液晶相变机制的有力工具。