Session Q27: Focus Session: New Trends in Spectroscopy III
11:15 AM–2:15 PM, Wednesday, March 17, 2010
Room: D137
Sponsoring Unit:
DCP
Chair: David Osborn, Sandia National Laboratories
Abstract ID: BAPS.2010.MAR.Q27.8
Abstract: Q27.00008 : Characterization of molecular crystal phonons
1:51 PM–2:03 PM
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Abstract 
Authors:
Rohit Singh
(Physics Dept., SUNY Buffalo)
Deepu George
(Physics Dept., SUNY Buffalo)
Andrea Markelz
(Physics Dept., SUNY Buffalo)
The terahertz frequency vibrational modes of molecular crystals can be used to determine polymorphism in pharmaceuticals and fundamental coupling between intramolecular and intermolecular motions [1]. As the molecular complexity increases, assignment of these modes becomes problematic with inhomogeneous broadening and increasing density of modes. Recently inhomogeneous broadening has been overcome by forming crystalline films on the surface of waveguides[2], however the inherent mode overlap for large systems is still problematic as the films formed are poly crystalline. Here we achieve mode separation by using single crystals and rapid modulation of the relative alignment of the terahertz polarization and the crystal axes by rotating the sample. The signal at the rotation frequency allows the rapid mapping out the optically active vibrational resonances along the different molecular and crystal orientations. 1. C.J. Strachan, P.F. Taday, D.A. Newnham, K.C. Gordon, J.A. Zeitler, M. Pepper, and T. Rades, J. Pharm. Sci., 2005. 94: p. 837-846. 2. J.S. Melinger, N. Laman, S.S. Harsha, S. Cheng, and D. Grischkowsky, J. Phys. Chem. A, 2007. 111: p. 10977-10987.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.Q27.8