Nonlocal Effects in the Plasmons of Strongly Interacting Nanoparticles, Dimers, and Waveguides

Abstract

Spatial nonlocality in the optical response of noble metals is shown to produce significant blue shift and near-field quenching of plasmons in nanoparticle dimers, nanoshells, and thin metal waveguides. Compared with a local description relying on the use of frequency-dependent dielectric functions, we predict resonance shifts as large as 10% and field-intensity reduction of an order of magnitude at interparticle distances or metal thicknesses below 2 A, although sizable effects are already observed for dimers separated by 2 nm. The calculation method (a combination of the specular-reflection model and a suitable nonlocal extension of measured local dielectric functions) is simple to implement and can be easily generalized to arbitrarily complex nanostructures.