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State-resolved THz Studies in the Gas and Condensed Phases

Wednesday, October 13, 2010- 4:00pm

CCU Lecture Series, National Radio Astronomy Observatory, Charlottesville


David Plusquellic

Research Physical Chemist, Optical Technology Division, NIST




State resolved THz studies of co-solvated crystalline peptides have provided a precise measure of the infrared active phonon modes that reflect motions on the longest possible length scales in these systems.  The impact of co-crystallized water on the lattice vibrations can range from subtle to dramatic depending on the hydrophobic or hydrophilic nature to the peptide water interactions.  These two classes of systems are investigated at the fully state resolved level using waveguide methods and periodic system calculations at the quantum and classical levels of theory. Across the periodic systems, new quantum chemical results on fully relaxed structures are now providing convincing evidence of phonon mode assignments and a detailed view of energetics responsible for the diverse dynamics displayed in these systems.  New chirped pulse THz instrumentation under development will also be discussed.  Several advantages are realized using phase coherent methods for studies of gas and condensed phase systems.