Code: TOG	Time Slot/Poster Number: 4:00 - 4:30 pm	Session: Sum Frequency Generation/Interfaces
Detection of Molecular Complexes and Direct Determination of Intermolecular Interaction Geometries by a Hybrid Raman-Infrared Multidimensional Coherent Spectroscopy
David Klug1; Guo Rui1; Elizabeth Gardner1; Margherita Miele1; Gould Ian1; Fournier Frederic1; Keith Willison2
1Imperial College, London, United Kingdom; 2Institute of Cancer Research, London, UK
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Summary
Electrical interactions between molecular vibrations can be non-linear and thereby produce intermolecular coupling even in the absence of a chemical bond. We use this fact to detect the formation of an intermolecular complex using a hybrid Raman-Infrared multidimensional coherent spectroscopy known as DOVE/EVV 2DIR. We go on to use this technique to determine the distance and angle between the two molecular species. Finally we predict the formation of new spectroscopic features for protein-protein and drug-protein interactions and present preliminary experimental results for such systems.

Code: TOG	Time Slot/Poster Number: 4:30 - 5:00 pm	Session: Sum Frequency Generation/Interfaces
Vibrational Coupling and Hydrogen Bonding at the Air/Water Interface
Alexander Benderskii
University of Southern California, Los Angeles, CA
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Summary
A combination of heterodyne-detected sum frequency generation (HD-SFG) vibrational spectroscopy and isotopic dilution studies was used to probe intra- and intermolecular vibrational couplings of the OD-stretch modes at the air-water interface of H2O:HOD:D2O mixtures. The “free OD” mode couples effectively only to the “other OD” mode on the same molecule, whose frequency can be extracted from the measurement. This reports on the average H-bond strength in the top-most layer at the water surface, which is found to be only slightly weaker than the bulk average.

Code: TOG	Time Slot/Poster Number: 5:00 - 5:20 pm	Session: Sum Frequency Generation/Interfaces
Interfacial Proteins and Peptides Studied Using Sum Frequency Generation Vibrational Spectroscopy
Zhan Chen
University of Michigan, Ann Arbor, MI
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Summary
Sum frequency generation (SFG) vibrational spectroscopy has been applied to investigate peptide and protein structures at interfaces, supplemented by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Various peptides and proteins including melittin, magainin 2, alamethicin, G-protein, fibrinogen, and tachyplesin I at various interfaces were studied in situ in real time. Systematic ways to deduce orientation distributions of interfacial α-helices, 3-10 helices, and beta-sheets have been developed.

Code: TOG	Time Slot/Poster Number: 5:20 - 5:40 pm	Session: Sum Frequency Generation/Interfaces
Creation and Relaxation of Phospholipid Compositional Asymmetry in Lipid Bilayers Examined by Sum-Frequency Vibrational Spectroscopy
Timothy Anglin; Krystal Brown; John Conboy
University of Utah, Salt Lake City, UT
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Summary
Using methods of classical surface chemistry coupled with sum-frequency vibrational spectroscopy (SFVS), we have developed a method to selectively probe lipid compositional asymmetry in planar supported lipid bilayers. This new method allows for the detection of lipid flip-flop kinetics and compositional asymmetry by exploiting the coherent nature of SFVS. The effect of lipid composition, headgroup and fatty acid chemical structure, on the rate and thermodynamics of lipid transbilayer migration and the electrostatic induction of lipid asymmetry will be discussed.

Code: TOG	Time Slot/Poster Number: 5:40 - 6:00 pm	Session: Sum Frequency Generation/Interfaces
AFM-Raman Imaging and Raman Spectral Fluctuation Analysis of Single-Molecule Interfacial Electron Transfer Dynamics
H Peter Lu
Bowling Green State University, Bowling Green, OH
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Summary
Interfacial electron transfer dynamics is important for environmental and catalytic reactions. Extensive ensemble-averaged studies have indicated inhomogeneous and complex dynamics of interfacial ET reaction. To characterize the complex mechanism, we have applied single-molecule spectroscopy and correlated AFM/STM imaging to study the interfacial ET dynamics of dye molecules adsorbed at the surface of TiO2 nanoparticles and charge transfer across biological interfaces. The interfacial ET activity of individual dye molecules showed fluctuations and intermittency at time scale of milliseconds to seconds.