Research
Research efforts in the group over the past few years have focused largely on acquiring and interpreting polarization-dependent nonlinear linear optical measurements of biopolymers, with a particular interest in understanding the mechanisms driving the high sensitivity of second harmonic generation (SHG) and sum-frequency generation (SFG) measurements to chirality.
Whereas the established analytical techniques of absorbance circular dichroism (CD) and optical rotary dispersion (ORD) yield relatively subtle changes due to chirality when compared to the analogous achiral properties of absorption and refraction, the chiral responses in second harmonic generation and sum-frequency generation are on the same order of magnitude as the achiral responses.
Furthermore, this chiral-specific response often originates from a single molecular monolayer in a diffraction-limited spot size, corresponding to a conservative detection limit of ~106 molecules required for chiral analysis.
Efforts to date have focused on two areas to address this problem:
1. The development of new experimental methods for acquiring precise nonlinear optical ellipsometry measurements in second harmonic generation and sum-frequency generation,
2. The development and validation of theoretical models for interpreting polarization-dependent measurements of biopolymer assemblies.
Research topics underway :
Copyright © 2010, Simpson Research Group, Department of Chemistry, Purdue University, all rights reserved
560 Oval Drive, West Lafayette, IN 47907