Temperature dependence of plasmon resonances in spheroidal metal nanoparticles

TL;DR

This paper investigates how electron temperature influences light absorption and scattering in metal nanoparticles, deriving formulas for optical properties at finite temperatures and analyzing size-dependent effects on plasmon resonances.

Contribution

It provides new analytical formulas for electroconductivity and polarizability tensors at finite electron temperatures in spheroidal metal nanoparticles.

Findings

Absorption efficiency can increase or decrease with temperature changes.

Surface plasmon resonance halfwidth varies with nanoparticle size and temperature.

Formulas enable calculation of optical phenomena for various nanoparticle shapes and media.

Abstract

The effect of the electron temperature on both the light absorption and the scattering by metal nanoparticles (MNs) with excitation of the surface plasmon electron vibrations is studied in the framework of the kinetic theory. The formulae for electroconductivity and polarizability tensors are derived for finite temperatures of an electron gas. The electrical conductivity and the halfwidth of the surface plasmon resonance are studied in detail for a spherical MN. Depending on the size of MN, the efficiencies of light absorption and scattering with the temperature change are investigated. It is found, in particular, that the absorption efficiency can both increase and decrease with a temperature drop. The derived formulas make it possible to analytically calculate various optical and transport phenomena for MNs of any spheroidal shape embedded in any dielectric media.