Surface plasmon in metallic nanoparticles: renormalization effects due to electron-hole excitations

TL;DR

This paper investigates how electron-hole excitations and spill-out effects influence the surface plasmon resonance in metallic nanoparticles, explaining experimental observations through theoretical and computational analysis.

Contribution

It introduces a comprehensive model combining spill-out effects and environment coupling to accurately predict plasmon resonance shifts in nanoparticles.

Findings

Both spill-out and environmental effects cause a redshift in resonance frequency.

The model agrees with experimental pump-probe spectroscopy data.

Resonance frequency depends on nanoparticle size and temperature.

Abstract

The electronic environment causes decoherence and dissipation of the collective surface plasmon excitation in metallic nanoparticles. We show that the coupling to the electronic environment influences the width and the position of the surface plasmon resonance. A redshift with respect to the classical Mie frequency appears in addition to the one caused by the spill-out of the electronic density outside the nanoparticle. We characterize the spill-out effect by means of a semiclassical expansion and obtain its dependence on temperature and the size of the nanoparticle. We demonstrate that both, the spill-out and the environment-induced shift are necessary to explain the experimentally observed frequencies and confirm our findings by time-dependent local density approximation calculations of the resonance frequency. The size and temperature dependence of the environmental influence results in a qualitative agreement with pump-probe spectroscopic measurements of the differential light transmission.