title: Real-space mapping of the strongly coupled plasmons of nanoparticle dimers.
abstract: We carried out the near-field optical imaging of isolated and dimerized gold nanocubes to directly investigate the strong coupling between two adjacent nanoparticles. The high-resolution (approximately 10 nm) local field maps (intensities and phases) of self-assembled nanocube dimers reveal antisymmetric plasmon modes that are starkly different from a simple superposition of two monomeric dipole plasmons, which is fully reproduced by the electrodynamics simulations. The result decisively proves that, for the closely spaced pair of nanoparticles (interparticle distance/particle size approximately 0.04), the strong Coulombic attraction between the charges at the interparticle gap dominates over the intraparticle charge oscillations, resulting in a hybridized dimer plasmon mode that is qualitatively different from those expected from a simple dipole-dipole coupling model.
authors.affiliation: Department of Chemistry and BK21 Division of Chemistry, Korea University, Seoul 136-701, Korea.
authors.forename: Deok-Soo
authors.initials: DS
authors.lastname: Kim
authors.forename: Jinhwa
authors.initials: J
authors.lastname: Heo
authors.forename: Sung-Hyun
authors.initials: SH
authors.lastname: Ahn
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Han
authors.forename: Wan Soo
authors.initials: WS
authors.lastname: Yun
authors.forename: Zee Hwan
authors.initials: ZH
authors.lastname: Kim