Gap-mode plasmonic nanocavity

Here we describe the fabrication and characterization of a plasmonic nanocavity formed in the narrow gap between a Ag nanowire and a flat Ag substrate. The fluorescence spectrum of nanocrystals within the gap was strongly modified by the cavity modes, showing peaks of position and width (Q similar to 30-60) in quantitative agreement with numerical calculations. At gap spacings of similar to 15 nm, the noncavity background fluorescence is largely quenched by the Ag substrate, while the modal fluorescence remains strong, indicating that gap-type structures are more robust to fluorescence quenching. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3505154]