Second Harmonic Ellipsometry and Spectroscopy of Biological Interfaces

在这个由化学系实验物理化学计划资助的项目中，普渡大学的Garth Simpson教授将使用基于表面二次谐波(SHG)产生和和频率产生(SFG)的非线性光学技术来研究生物分子在表面上的手性。与传统的基于吸光度的方法相比，倍频偏振测量对界面手性的敏感度高出几个数量级。这项研究的目的是从根本上了解生物界面的非线性光学性质，从而为解释这类系统的未来研究奠定基础。本项目的研究包括三个具体的任务：1)阐明在有序手性薄膜的非线性光学测量中产生大手性效应的机制；2)发展非线性光学零椭圆偏振测量法，作为一种新的和稳健的方法来获取和解释取向的手性和非手性表面系统的非线性偏振测量；以及3)进行模型脂和蛋白质脂界面的非线性光学测量，为解释更复杂的生物系统的非线性光学测量提供背景。除了这些基础研究之外，辛普森教授还将通过普渡大学理科试点项目开发适用于K-12教育的激光仪器模块。这项计划以印第安纳波利斯公立学校7至12年级的学生为目标，通过三个组成部分：1)课外计划；2)后续活动；3)指导教师专业发展。

In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Prof. Garth Simpson of Purdue Universty will investigate the chirality of biological molecules on surfaces using nonlinear optical techniques based on surface second harmonic (SHG) generation and sum frequency generation (SFG). SHG polarization measurements are by several orders of magnitude more sensitive to interfacial chirality than traditional absorbance-based methods. The goal of this research is to gain a fundamental understanding of the nonlinear optical properties of biological interfaces and thereby establish a foundation for interpreting future studies of such systems. The research component of this project consists of three specific tasks: 1) to elucidate the mechanisms responsible for the large chiral effects in nonlinear optical measurements of ordered chiral films; 2) to develop nonlinear optical null ellipsometry as a novel and robust approach for acquiring and interpreting nonlinear polarization measurements of oriented chiral and achiral surface systems; and 3) to make nonlinear optical measurements of model lipid and proteolipid interfaces to provide a context in which to interpret nonlinear optical measurements of more complex biological systems. Graduate and undergraduate students as well as postdoctoral research associates will participate in the research.In addition to these fundamental investigations Prof. Simpson will develop laser instrumentation modules suitable for use in K-12 Education through the Purdue University Science Bound pilot program. This program targets 7th through 12th grade students in the Indianapolis Public Schools by means of three components: 1) after school programs; 2) follow-up activities; and 3) mentor teacher professional development.