Plasmonic tunnel junctions for single-molecule redox chemistry
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Peer-reviewed
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Abstract
Nanoparticles attached just above a flat metallic surface can trap optical fields in the nanoscale gap. This enables local spectroscopy of a few molecules within each coupled plasmonic hotspot, with near thousand-fold enhancement of the incident fields. As a result of non-radiative relaxation pathways, the plasmons in such sub-nanometre cavities generate hot charge carriers, which can catalyse chemical reactions or induce redox processes in molecules located within the plasmonic hotspots. Here, surface-enhanced Raman spectroscopy allows us to track these hot-electron-induced chemical reduction processes in a series of different aromatic molecules. We demonstrate that by increasing the tunnelling barrier height and the dephasing strength, a transition from coherent to hopping electron transport occurs, enabling observation of redox processes in real time at the single-molecule level.
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2041-1723
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Engineering and Physical Sciences Research Council (EP/K028510/1)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (702005)
Engineering and Physical Sciences Research Council (EP/G060649/1)
European Commission (658360)
Engineering and Physical Sciences Research Council (EP/L027151/1)