Garth J. Simpson
College of Science
West Lafayette, IN 47907
- Phone: 7654963054
Our interests lie in developing new instrumental methods capable of exploring nanoscale structural changes under ambient conditions. Current bioenergy related efforts include the development of an imaging nonlinear optical ellipsometer (NSF-MRI-ID) in collaboration with Michael Ladisch, Nathan Mosier, and Christopher Staiger. When complete, the instrument is expected to enable in situ monitoring of structural reorganization within cellulosic materials during the processes of cell wall formation and deconstruction. Unlike traditional optical imaging, nonlinear optical microscopy is exquisitely sensitive to local structure and order. A key element in this effort is the combination of nonlinear optical imaging, detailed polarization characterization, analytical theory, and computational chemistry to help relate the macroscopic measurements to the molecular-scale frame.
In addition to the optical imaging methods described above, our research group has devoted considerable effort in the development of new scanning probe microscopy techniques optimized for imaging under aqueous conditions. Specifically, we have combined dielectrophoresis (mobility of polarizable particles in radio-frequency AC electric fields) with atomic force microscopy to allow non-contact imaging in which changes in the local AC polarizability is used for feedback. More recently, we have been working to develop new platforms for piezoelectric force microscopy with nano-scale spatial resolution, in which the peizoresponse of biomaterials is a direct indicator of local molecular-scale order.
Expertise: Nonlinear optics – relating polarization-dependence with molecular-scale structure
Nonlinear optical microscopy
Nanoscale imaging using novel scanning probe microscopy techniques
B.S., Western Washington University, 1995
Ph.D., University of Colorado, 2000