Illuminating Dark Plasmons of Silver Nanoantenna Rings to Enhance Exciton-Plasmon Interactions

The chemical growth of silver nanorings that possess singly twinned crystals and a circular cross section via a reductive reaction solution is reported. The wire and ring diameters of the synthesized nanorings are in the ranges 80 200 nm and 4.5-18.0 mu m, respectively. By lighting up the multipolar dark plasmons with slanted illumination, the silver nanoring exhibits unique focused scattering and large local-field enhancement. We also demonstrate strong exciton-plasmon interactions between a monolayer of CdSe/ZnS nanoring semiconductor quantum dots and a single silver antenna-like (nanoantenna) at the hot spots located at the cross points of the incident plane and nanoring; the position of these spots are tunable by adjusting the incidence angle of illumination. The tunable plasmonic behavior of the silver nanorings could find applications as optical nanoantennae or plasmonic nanocavities.