Mie scattering by a charged dielectric particle

TL;DR

This paper investigates how surplus electrons influence Mie scattering in dielectric particles, revealing shifts in infrared extinction resonances that enable optical charge measurement for plasma applications.

Contribution

It introduces a novel method to detect particle charge via shifts in infrared scattering resonances caused by surplus electrons.

Findings

Surplus electrons cause a measurable shift in the infrared extinction resonance.

The effect depends on electron affinity and conductivity mechanisms.

This method enables non-invasive charge measurement in plasma environments.

Abstract

We study for a dielectric particle the effect of surplus electrons on the anomalous scattering of light arising from the transverse optical phonon resonance in the particle's dielectric constant. Excess electrons affect the polarizability of the particle by their phonon-limited conductivity, either in a surface layer (for negative electron affinity) or the conduction band (for positive electron affinity). We demonstrate that surplus electrons shift an extinction resonance in the infrared. This offers an optical way to measure the charge of the particle and thus to use it in a plasma as a minimally invasive electric probe.