title: Theta-shaped plasmonic nanostructures: bringing "dark" multipole plasmon resonances into action via conductive coupling.
abstract: Quadrupole plasmon and (octupolar) Fano resonances are induced in lithographically fabricated theta-shaped ring-rod gold nanostructures. The optical response is characterized by measuring the light scattered by individual nanostructures. When the nanorod is brought within 3 nm of the ring wall, a weak quadrupolar resonance is observed due to capacitive coupling, and when a necklike conductive bridge links the nanorod to the nanoring the optical response changes dramatically bringing the quadrupolar resonance into prominence and creating an octupolar Fano resonance. The Fano resonance is observed due to the destructive interference of the octupolar resonance with the overlapping and broadened dipolar resonance. The quadrupolar and Fano resonances are further enhanced by capacitive coupling (near-field interaction) that is favored by the theta-shaped arrangement. The interpretation of the data is supported by FDTD simulation.
authors.affiliation: Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Terefe G
authors.initials: TG
authors.lastname: Habteyes
authors.forename: Scott
authors.initials: S
authors.lastname: Dhuey
authors.forename: Stefano
authors.initials: S
authors.lastname: Cabrini
authors.forename: P James
authors.initials: PJ
authors.lastname: Schuck
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Leone
mesh_terms: D003198:Computer Simulation; D004553:Electric Conductivity; D006046:Gold / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D006046:Gold