Strong coupling between a metallic nanoparticle and a single molecule

We theoretically investigate the strong coupling between a single molecule and a single metallic nanoparticle. A theory suited for the quantum-mechanical description of surface plasmon polaritons (SPPs) is developed. The coupling between these SPPs and a single molecule, and the modified molecular dynamics in the presence of the nanoparticle are described within a combined Drude and boundary-element-method approach. Our results show that strong coupling is possible for single molecules and metallic nanoparticles and can be observed in fluorescence spectroscopy through the splitting of emission peaks.