Quantum plasmonics: Symmetry-dependent plasmon-molecule coupling and quantized photoconductances
We investigate photoinduced electron transport through nanoparticle dimers connected by linear and ringlike molecules. The two model junctions exhibit similar absorption but distinct photoconductance. The linear-chain junction shows a constant conductance that is independent of photon energies. In contrast, the ring molecules show quantized conductance resonances at energies corresponding to the molecular excitations. These results can be understood from the symmetry and quantization of local molecular excitations, and have implications for plasmon-molecule interactions in general.