Anisotropic response in molecular crystals and the development of Modulated Orientation Sensitive Terahertz Spectroscopy (MOSTS) – Andrea Markelz

Date: Mon. March 19th, 2012, 12:30 pm-1:30 pm
Location: Rockefeller 221

Since the mid 1980’s there have been predictions of protein structural vibrations with ~ 1meV energies, which corresponds to the terahertz frequency range. These large scale motions involve the correlated movement of many atoms and are associated with the conformational motions involved in protein function. There have been many attempts to measure these modes, but the energy range overlaps with that of local librational motions of the surface side chains and the solvent, and these contributions give rise to a strong glass-like response. In this talk I will discuss our development of a technique to isolate the large scale structural contribution from a glassy background called Modulated Orientation Sensitive Terahertz Spectroscopy (MOSTS). I will present characterization of the technique using molecular crystals and a protein crystal model system to demonstrate the ability of the technique to isolate the anisotropic response.