On Surface Plasmon Damping in Metallic Nanoparticles

TL;DR

This paper theoretically investigates two mechanisms of surface plasmon damping in metallic nanoparticles, focusing on radiation damping and resonant coupling with electronic transitions, highlighting size-dependent effects.

Contribution

It identifies and analyzes two non-electron-phonon damping mechanisms in metallic nanoparticles, emphasizing their dependence on particle size and matrix properties.

Findings

Radiation damping rate scales with the number of electrons in the nanoparticle.

Energy leakage via resonant coupling depends on matrix characteristics, not particle size.

Small nanoparticles exhibit effective damping through resonant coupling due to size quantization.

Abstract

Two possible mechanisms of surface plasmon (SP) oscillations damping in metallic nanoparticles (MNPs), not connected with electron-phonon interaction are investigated theoretically: a) the radiation damping of SP, b) resonant coupling of SP oscillations with electronic transitions in matrix. It is shown that the radiation damping rate is proportional to the number of electrons in MNP and therefore this channel of energy outflow from MNP becomes essential for relatively large particles. The investigation of second mechanism shows that the rate of SP oscillations energy leakage from MNP dos not depend on particle size and is fully determined by the optical characteristics of the matrix. It is demonstrated that for very small MNPs of 3-5 nm size, where the strong 3D size quantization effect suppresses the electron-phonon interaction, the resonance coupling in certain cases provides an effective energy outflow.