Amplified Plasmonic Forces from DNA Origami-Scaffolded Single Dyes in Nanogaps

초록

Developing highlyenhanced plasmonic nanocavities allowsdirectobservation of light-matter interactions at the nanoscale.With DNA origami, the ability to precisely nanoposition single-quantumemitters in ultranarrow plasmonic gaps enables detailed study of theirmodified light emission. By developing protocols for creating nanoparticle-on-mirrorconstructs in which DNA nanostructures act as reliable and customizablespacers for nanoparticle binding, we reveal that the simple pictureof Purcell-enhanced molecular dye emission is misleading. Instead,we show that the enhanced dipolar dye polarizability greatly amplifiesoptical forces acting on the facet Au atoms, leading to their rapiddestabilization. Using different dyes, we find that emission spectraare dominated by inelastic (Raman) scattering from molecules and metals,instead of fluorescence, with molecular bleaching also not evidentdespite the large structural rearrangements. This implies that thecompetition between recombination pathways demands a rethink of routesto quantum optics using plasmonics.

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