Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles

TL;DR

This paper investigates how the size of simple metal nanospheres influences their multipolar plasmon resonance frequencies and damping rates, providing a rigorous analysis within the Drude-Sommerfeld model and comparing with experimental sodium nanodroplets.

Contribution

It offers a size-dependent, non-approximated analysis of multipolar plasmon resonances in metal nanospheres, incorporating effects of dielectric surroundings and interband transitions.

Findings

Resonance frequencies depend on particle size and environment.

Damping rates vary with size and plasmon mode.

Experimental sodium nanodroplet data aligns with theoretical predictions.

Abstract

Multipolar plasmon oscillation frequencies and corresponding damping rates for nanospheres formed of the simplest free-electron metals are studied. The possibility of controlling plasmon features by choosing the size and dielectric properties of the sphere surroundings is discussed. Optical properties of the studied metals are described within the Drude-Sommerfeld model of the dielectric function with effective parameters acounting for the contribution of conduction electrons and of interband transitions. No approximation is made in respect of the size of a particle; plasmon size characteristics are described rigorously. The results of our experiment on sodium nanodroplets [1] are compared with the oscillation frequency size dependence of dipole and quadrupole plasmon.