Enhanced fluorescence transduction properties of metallic nanocavity arrays

We studied fluorescence enhancement of molecular species bound within metallic nanocavities. These nanostructures possess a number of desirable properties for real-time microarrays, such as localization of excitation light within the nanocavities, strong isolation from fluorescence produced by unbound species, and an apparent increase in fluorescence yield for bound species. Experimental measurements show nearly a factor of two increase in excitation intensity within the nanocavities, and factor of six increase in yield. A simple electromagnetic model of a dipole within a nanocavity shows an increase in radiative output consistent with our yield estimates, and also verifies the strong fluorescence isolation from species lying outside the nanocavity.