Hybridization of plasmon modes in multishell bimetallic nanoparticles: a numerical study

We study the near-infrared properties of spherical multishell nanoparticles comprising a loss-less dielectric core enclosed by a concentric layering of metallic–dielectric–metallic nanoshells. The coupling between the metallic shells induces plasmon resonance redshifts and peak splitting in the absorption spectra of the layered particle relative those of the metallic constituents. We use full-wave electromagnetic analysis to investigate changes in the absorption spectra as a function of key parameters including the material properties of the inner and outer metallic shells and the aspect ratio of their inner and outer radii. We systematically vary the aspect ratios and quantify the degree of plasmonic coupling between the metallic nanoshells. Our analysis reveals conditions under which the spectral resonance peaks blueshift and/or redshift. We consider bimetallic particles with gold and silver nanoshells and determine the dependency of plasmon resonance peak shifting and splitting as a function of the order of these material layers, i.e., as inner or outer shells.