Plasmonic Behavior of Single Gold Dumbbells and Simple Dumbbell Geometries

Dumbbell-shaped nanoparticles are similar in size to their nanorod counterparts, but their optical properties have not been studied as extensively as the nanorod. In this paper, the spectra of a single dumbbell, several dumbbell dimers, and a pentamer were collected experimentally and compared with simulated spectra. Surface charge density plots were also obtained in order to elucidate the nature of the plasmonic modes. The dumbbell is shown to be a particle that acts as a transition from the nanorod to the nanosphere. Because the dumbbell shape allows adjacent particles to interlock like puzzle pieces, dumbbells can be thought of as optical building blocks that can combine into designs that are capable of supporting localized hot spots, Fano resonance, and tunable plasmon peaks.