Polarization Dependent Nonlinear Optical Properties of Biomolecules

Purdue University, West Lafayette IN

Investigators

Abstract

Garth Simpson of Purdue University is supported by the Experimental Physical Chemistry Program to develop a systematic framework that will provide a foundation for interpreting polarization-dependent nonlinear optical (NLO) measurements of oriented biomolecular assemblies. The primary objectives are to: (1) refine and test computational methods based on perturbation theory for describing the polarization-dependent NLO properties of biopolymers, (2) develop new instrumental methods for detailed polarization analysis in second harmonic generation (SHG), sum frequency generation (SFG), and two-photon absorption, and (3) assess the range of validity of the perturbation theory approach from combined electronic SHG, vibrational SFG, and electronic two-photon absorption measurements of model oriented bacteriorhodopsin thin films and collagen fibrils. Nonlinear optical methods have great promise as probes to understand microscopic structure in biological systems. This project will enable significant development of new techniques that can be used effectively in chemistry and biology. The useful impacts of this work will be extended to the broader community with the continued development of the freely distributed software package NLOPredict, and initiation and organization of a new annual summer meeting on nonlinear optics.