Surface Plasmons in the Continuum

TL;DR

This paper introduces a time-dependent density-functional theory approach to accurately model surface plasmons in the ultraviolet spectrum, accounting for ionization effects in aluminum clusters.

Contribution

It presents a robust ab initio method to describe surface plasmons in the continuum, including ionization, for aluminum clusters.

Findings

Accurate modeling of surface plasmons in the UV range.

Size-dependent evolution from discrete features to broad plasmon resonance.

Application to Al13- demonstrates the method's effectiveness.

Abstract

The interest to foster plasmonic applications at energies in the ultra-violet, has escalated research initiatives in clusters of unconventional plasmonic materials like aluminum and indium,for which the surface-plasmon resonance appears above the ionization potential. Naturally, the quantum mechanical description calls for the incorporation of the ionization process, thereby making the ab initio calculations challenging. We present a robust approach within the time-evolution formalism of the time-dependent density-functional theory to calculate surface plasmon resonance in the continuum of metal clusters. Using the much studied Al$_{13}^-$ as a system of reference, we show that accurate description of the continuum and of the ionization of the cluster allow to capture a broad surface-plasmon in the UV. Application of this approach in aluminum clusters has given the size-dependent evolution from discrete spectral features in Al$_{6}$ to the surface-plasmon in larger clusters in the deep ultra-violet.