Inelastic fingerprints of hydrogen contamination in atomic gold wire systems

TL;DR

This study uses first-principles calculations to analyze how hydrogen impurities affect the conductance and inelastic signals of atomic gold wires, providing a potential method for detecting such contamination.

Contribution

It introduces a detailed theoretical analysis of hydrogen contamination effects on gold wires, highlighting inelastic signals as a detection method.

Findings

Hydrogen slightly reduces conductance in gold wires.

Inelastic signals differ significantly between pure and hydrogen-contaminated wires.

Strain dependence of inelastic signals can characterize hydrogen impurities.

Abstract

We present series of first-principles calculations for both pure and hydrogen contaminated gold wire systems in order to investigate how such impurities can be detected. We show how a single H atom or a single H2 molecule in an atomic gold wire will affect forces and Au-Au atom distances under elongation. We further determine the corresponding evolution of the low-bias conductance as well as the inelastic contributions from vibrations. Our results indicate that the conductance of gold wires is only slightly reduced from the conductance quantum G0=2e^2/h by the presence of a single hydrogen impurity, hence making it difficult to use the conductance itself to distinguish between various configurations. On the other hand, our calculations of the inelastic signals predict significant differences between pure and hydrogen contaminated wires, and, importantly, between atomic and molecular forms of the impurity. A detailed characterization of gold wires with a hydrogen impurity should therefore be possible from the strain dependence of the inelastic signals in the conductance.