Optimization of Three-Layered Au-Ag Bimetallic Nanoshells for Triple-Bands Surface Plasmon Resonance

Plasmonic light absorption properties of three-layered Au-Ag bimetallic nanoshells are investigated using the quasi-static electricity and plasmon hybridization theory. Comparing with Audielectric-Au and Ag-dielectric-Au multilayer nanoshells, Au-dielectric-Ag multilayer nanoshells are demonstrated more suitable for triple-bands surface plasmon resonance (SPR). Calculation results indicated that the triple plasmon resonance in Au-dielectric-Ag multilayer nanoshells could be optimized by choosing appropriate geometrical dimensions of the inner gold sphere and outer silver shell. The corresponding physical mechanism has also been illustrated by analyzing the surface charge distribution and intercoupling of the polarization fields from different metal-dielectric interfaces. This triple-bands SPR in the bimetallic multilayer nanostructure provides potential for multiplex biosensing based on SPR absorption, surface enhanced fluorescence, and surface enhanced Raman scattering (SERS).