Design of multipolar plasmon excitations in silver nanoparticles

Abstract

We report on the experimental observation of multipolar plasmon excitations in lithographically designed elongated silver particles. In contrast to spheres, where the extinction bands of the respective multipolar plasmons overlap considerably to form a broad spectrum, spectrally well-separated extinction bands corresponding to plasmons of multipolar order up to n=6 are found. The results agree well with numerical simulations based on the Green’s Dyadic method.

Plasmon-enhanced photocurrent generation and water oxidation from visible to near-infrared wavelengths

“…13,33 As a result, a dipole and quadrupole form because a charge bias arises on the surface of the metallic nanoparticle. 13,[34][35][36][37] Furthermore, because an electric field arises as a result of the differential electronic charge, localized electromagnetic waves, also called 'near-field light' , form on the metallic particle surface. This near-field light differs from ordinary light (light that can be propagated, also called propagating light), and is localized in the vicinity of the metallic surface.…”

Defect-induced activation of symmetry forbidden infrared resonances in individual metallic nanorods

“…From the mid to far infrared ͑IR͒, for gold nanorods with micrometer lengths ͑and L / D Ͼ 10͒, n 1 becomes very small and res =2 p n 2 −1 L = bL which is a relation like that of an ideal antenna where b =2. Besides the strong fundamental ͑l =1͒ mode, such nanoantennas also exhibit multipolar ͑l Ͼ 1͒ resonances at res / l. 9,[12][13][14] Only multipolar modes with an antisymmetric charge distribution ͑odd l͒ can be optically excited at normal incidence of light because their total dipole moment does not vanish. 13,15 In contrast to these bright modes, plasmonic excitations with a centrosymmetric charge distribution ͑even l͒ ͑Ref.…”

Investigation of metallic nanowire-based localized surface plasmon resonance optical biosensors using extinction spectra

“…These additional extinction peaks originate from the excitation of higher order harmonics of multipolar plasmon oscillations, induced by the complex nanowire profile. Since the optical near-field distribution around a nanostructure is affected by the order of excited multipolar plasmon modes, which modify optical properties of metallic nanowires intricately, 33 the extinction spectra also present a less linear sensitivity characteristic to binding biomolecular changes. The extinction effects of the T-profile on the refractive index sensitivity are shown in Fig.…”