Measurement of discrete energy-level spectra in individual chemically-synthesized gold nanoparticles

TL;DR

This study measures discrete energy levels in individual gold nanoparticles using single-electron transistors, revealing non-magnetic properties and spectra consistent with random-matrix theory considering spin-orbit effects.

Contribution

First direct measurement of energy-level spectra in single chemically-synthesized gold nanoparticles with detailed comparison to theoretical predictions.

Findings

Gold nanoparticles are non-magnetic.

Energy spectra agree with random-matrix theory.

Strong spin-orbit coupling influences spectra.

Abstract

We form single-electron transistors from individual chemically-synthesized gold nanoparticles, 5-15 nm in diameter, with monolayers of organic molecules serving as tunnel barriers. These devices allow us to measure the discrete electronic energy levels of individual gold nanoparticles that are, by virtue of chemical synthesis, well-defined in their composition, size and shape. We show that the nanoparticles are non-magnetic and have spectra in good accord with random-matrix-theory predictions taking into account strong spin-orbit coupling.