Undamped energy transport by collective surface plasmon oscillations along metallic nanosphere chain

TL;DR

This paper develops a semiclassical scheme to analyze plasmon excitations in large metallic nanospheres, revealing undamped surface plasmon wave propagation along chains and comparing damping effects with experimental data.

Contribution

It introduces a new semiclassical approach for plasmon excitations in large nanospheres, including surface and volume modes, and studies collective surface plasmon waves in nanosphere chains.

Findings

Only dipole surface plasmons are excited by homogeneous fields.

Identified undamped plasmon wave propagation in nanosphere chains.

Resonance frequency shifts match experimental data.

Abstract

The random-phase-approximation semiclassical scheme for description of plasmon excitations in large metallic nanospheres (with radius 10--100 nm) is developed for a case of presence of dynamical electric field. The spectrum of plasmons in metallic nanosphere is determined including both surface and volume type excitations and their mutual connections. It is demonstrated that only surface plasmons of dipole type can be excited by a homogeneous dynamical electric field. The Lorentz friction due to irradiation of e-m energy by plasmon oscillations is analysed with respect to the sphere dimension. The resulting shift of resonance frequency due to plasmon damping is compared with experimental data for various sphere radii. Collective of wave-type oscillations of surface plasmons in long chains of metallic spheres are described. The undamped region of propagation of plasmon waves along the chain is found in agreement with some previous numerical simulations.