Second Harmonic Ellipsometry and Spectroscopy of Biological Interfaces

Purdue University, West Lafayette IN

Investigators

Abstract

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.