Dynamic modifications of polarizability for large metallic spheroidalnanoshells

摘要

We present an approach alternative to the hybridization model for the treatment of the coupledinterfacial plasmon modes in spheroidal metallic nanoshells. Rather than formulating the problemfrom the Lagrangian dynamics of the free electronic fluid, we adopt an effective medium approach together with the uniqueness of the solutions to electromagnetic boundary value problem, fromwhich the polarizability of the shells can then be systematically and efficiently derived; and the resonance frequencies for the coupled modes can be obtained from the poles in the polarizability.This approach can treat confocal nanoshells with different geometries for the spheroidal cavity andexternal surface and allow for a natural extension to incorporate corrections from the finiteness of the optical wavelength which are important for nanoparticles of larger sizes. This thus surpasses thehybridization model which is limited to incorporate only the electrostatic Coulomb interactionbetween the uncoupled plasmons. Numerical results will be provided for different nanoshell systems, and for the illustration of the various geometric and dynamic effects from our model.