Abstract
We clarify mechanistic questions regarding plasmon-driven chemistry and nanoscale photocatalysis within optically confined near-field plasmonic systems. Using surface-enhanced Raman scattering (SERS), we directly monitor the photoinduced reaction dynamics of 4,4′-bipyridine molecules, localized in plasmonic hot spots within individual gold nanosphere oligomers. Our experiment generates surface electrons from the gold nanoparticle using an intense off-molecular resonance continuous wave pump field, and detects radical anion products via SERS. This is done by adopting a dual-wavelength spectroscopic approach. Empirical evidence of plasmon-driven electron transfer is provided for the first time by direct detection of the 4,4′-bipyridine radical anion species localized in the plasmonic hot spots of individual gold nanosphere oligomers, corroborated by open-shell density functional theory calculations. An isotopologue approach using both protonated and deuterated 4,4′-bipyridine molecules demonstrates the single molecule response of plasmon-driven electron transfer occurring in single nanosphere oligomer systems with a 3% yield, a phenomenon unobserved in ensemble measurements under analogous experimental conditions. This mechanism has broad applicability to using nanoscale chemical reactors for surface redox reactions on the subnanometer scale.
Original language | English (US) |
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Pages (from-to) | 15212-15221 |
Number of pages | 10 |
Journal | Journal of the American Chemical Society |
Volume | 139 |
Issue number | 42 |
DOIs | |
State | Published - Oct 25 2017 |
Funding
E.A.S.-K., M.O.M., V.A.A., G.C.S., and R.P.V.D. were supported by the National Science Foundation Center for Chemical Innovation dedicated to Chemistry at the Space-Time Limit (CaSTL) Grant CHE-1414466. E.A.S.-K. and M.O.M. acknowledge support from the National Science Foundation Graduate Research Fellowship Program (DGE-0824162). D.V.Z. and T.S. acknowledge support from the National Science Foundation Grant CHE-1465201. A.B.Z. and R.P.V.D. acknowledge support from the National Science Foundation (CHE-1506683). The authors would also like to thank Northwestern University’s Atomic and Nanoscale Characterization Experimental Center (NUANCE) for the use of their imaging facilities.
ASJC Scopus subject areas
- Catalysis
- General Chemistry
- Biochemistry
- Colloid and Surface Chemistry