Theoretical study of single molecule fluorescence in a metallic nanocavity

A theoretical study is presented on the fluorescence excitation and emission of a molecule embedded within a nanometric metal-coated dielectric bead. It occurs that, for favorable values of bead radius and metal layer thickness, photostability of the molecule is improved significantly, due to a dramatic decrease of the fluorescence lifetime caused by the strong electromagnetic interaction between the emitting molecule and the metal layer. Moreover, the metal shell enhances the exciting electric field intensity leading to an increase in fluorescence brightness by more than one order of magnitude.