Abstract: Plasmons hold great promise for photon conversion and coherent energy transport at the nanoscale. Following visible light excitation of collective conduction electrons near the surface of nanostructures, hot charge carriers are created via nonradiative relaxation pathways that are then harnessed to drive localized chemical transformations of individual molecules. Limited knowledge of the precise mechanisms underlying plasmon-mediated chemistry in nanogaps currently restricts widespread technological applications, which in turn has generated substantial fundamental research interest in surface-molecule dynamics.

In this talk, I demonstrate the first direct observation of the molecular anion radical probed by using vibrational spectroscopy within optically confined near-field plasmonic substrates. Corroboration of the anion radical species formed within the solid state is provided by open-shell density functional theory, resonance Raman, and electron paramagnetic resonance spectroscopy.

I then investigate the wavelength tunability of plasmon-driven electron transfer as well as the spectrally resolved polarization response of individual nanoparticles with correlated far-field scattering and high-resolution transmission electron microscopy. Use of this new energetic pathway can be applied to basic energy research with the potential for profound impact on next-generation light-harvesting nanoscale devices.