Measurement of the complex dielectric constant of a single gold nanoparticle

TL;DR

This study uses a novel microscopy technique to measure the complex dielectric constant of individual gold nanoparticles, revealing deviations from bulk gold properties at certain wavelengths.

Contribution

It introduces a differential interference contrast microscopy method employing a photonic crystal fiber to measure dielectric properties of single nanoparticles.

Findings

Deviations from bulk gold dielectric constants at short wavelengths.

Differences observed between 10 nm and 15 nm nanoparticles.

Finite-size surface damping effects partially explain the deviations.

Abstract

A differential interference contrast microscopy technique, which employs a photonic crystal fiber as a white-light source, is used to measure both the real and imaginary parts of the complex dielectric constant of single 10 and 15 nm gold nanoparticles over a wavelength range of 480 to 610 nm. Noticeable deviations from bulk gold measurements are observed at short wavelengths and for individual particles even after taking into account finite-size surface damping effects.