Molecular Plasmonics: Single Molecule and Ultrafast Surface-Enhanced Raman Spectroscopy

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With this project, the Chemical Measurement and Imaging Program of the Chemistry Division is funding Professor Richard P. Van Duyne of Northwestern University to explore two new spectroscopic techniques. One of these can detect and identify individual molecules as they bind to surfaces and chemically react. The other can measure molecular structure changes on ultrafast timescales similar to that for a molecule to vibrate just once. In other words, we are aiming to take molecular snapshots of single molecules doing chemistry. This project has substantial promise to advance knowledge in a broad range of fields including healthcare, communications, chemical analysis and imaging. The project will provide interdisciplinary training for graduate student researchers on the Van Duyne team.This project focuses on advances in the application two new spectroscopic techniques to the field of molecular plasmonics. The first is single molecule surface-enhanced Raman spectroscopy (SMSERS). At present, SMSERS is the only technique that can both detect and identify a single molecule in ambient, gas, or liquid environments. SMSERS will be used to probe more deeply into the fundamental interactions between molecules and surfaces. The second technique is surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS). The fundamental light-matter interaction mechanism of SE-FSRS will be investigated through systematic studies of laser power dependence, polarization dependence, and spectral relations between the laser pulses and the plasmon resonance(s) of the nanoparticles used as substrates. Ultimately the goal is to probe the reactivity of surface bound molecules at the intrinsic femtosecond timescales of chemistry. Van Duyne's research program has developed this subdiscipline of SERS and related plasmonic spectroscopies. These methods are now major analytical tools in chemistry, physics, materials science biomedical engineering, and biology. This project seeks to continue to extend the impact of plasmonic spectroscopy on surface science, chemical measurements at the limits of sensitivity and time scale, chemical and biological imaging, electrochemistry, catalysis, art conservation and cultural heritage science.