Electron Temperature Dependence of the Optical Properties of Small Sodium Nanoparticles

TL;DR

This study investigates how the electron temperature affects the optical properties of small sodium nanoparticles, revealing a unique temperature-dependent behavior of the surface plasmon linewidth with potential experimental verification.

Contribution

It introduces a new model for analyzing electron temperature effects on plasmon linewidths and links size uncertainty to intrinsic linewidth in small nanoparticles.

Findings

Surface plasmon linewidth decreases with electron temperature.

Linewidth exhibits a sudden drop at high electron temperatures.

Size uncertainty contributes to intrinsic linewidth in small clusters.

Abstract

We report a novel behavior of the surface plasmon linewidth in sodium nanospheres Na$_{1760}$ changing with the electron temperature, which monotonically decreases and bears a discontinuous sudden drop at high electron temperatures. Our calculation is based on the model constructed by splitting the total Hamiltonian of all valence electrons of a metallic nanoparticle into two sub-Hamiltonians and their coupling, and obtained results can be verified by the pump-probe femtosecond spectroscopy experiments. In addition, we propose that it is the size uncertainty of small nanoparticles that yields the intrinsic linewidth of the surface plasmon resonance, which is supported by the available data of clusters Na$_{8}$ and Na$_{20}$.