Plasmon-Driven Chemistry as Revealed by Ultrafast SERS, Single Molecule SERS, and Electrochemical TERS

Northwestern University, Evanston IL

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Van Duyne at Northwestern University is conducting studies to better understand how molecules behave and chemical reactions happen in the presence of a strong electromagnetic (EM) field induced by nearby plasmonic nanoparticles. Surface plasmon is a phenomenon from the oscillation of electrons on the surface of plasmonic nanoparticles collectively. Many factors affect how strong the EM field (i.e. the plasmonic field) is and how a molecule closely behaves. Professor Van Duyne plans to investigate the fundamental mechanisms of plasmon-driven chemistry, study the chemical enhancement contribution to single-molecule using a technique called surface-enhanced Raman spectroscopy (SM-SERS), and develop an electrochemical tip-enhanced Raman spectroscopy (EC-TERS) to interrogate how charge transfer across interfaces during chemical reactions. Fundamental insight gained from his study could enable new technological applications including photocatalysis, electrocatalysis, energy conversion and advance a wide array of technologies in multiple sectors including biosensing, defense, and healthcare. Professor Van Duyne works close with his graduate students and postdoctoral fellows, many women students, in his research group. He also plans to continue his outreach efforts to the public by hosting high school teachers in summers and interact with kids and their parents at an All Scout Nano Day on campus. Surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) is applied to yield reaction mechanistic information across multiple time scales. In order to generalize single molecule surface-enhanced Raman spectroscopy to small molecules, chemical enhancement contribution is investigated to provide additional signal enhancement to boost the sensitivity of SMSERS. Professor Van Duyne plans to develop Electrochemical tip-enhanced Raman spectroscopy (EC-TERS) to elucidate the mechanisms of heterogeneous charge transfer reactions. EC-TERS can provide chemical information with spatial resolution down to the single site limit. Both fundamental understanding and novel applications of plasmonics on the nano and molecular scale is anticipated to be advanced through the proposed research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.