Identification of the Molecule-Metal Bonding Geometries of Molecular Nanowires

TL;DR

This paper demonstrates that inelastic tunneling spectroscopy (IETS) can be used to determine the bonding geometries of molecular nanowires, specifically at gold-sulfur interfaces, through ab initio calculations matching experimental signatures.

Contribution

It introduces a method using ab initio calculations to identify molecule-metal bonding geometries via IETS, addressing a longstanding experimental challenge.

Findings

IETS signatures can distinguish different bonding geometries.

Ab initio calculations match experimental IETS data.

Gold-sulfur interface geometries are identified.

Abstract

Molecular nanowires in which a single molecule bonds chemically to two metal electrodes and forms a stable electrically conducting bridge between them have been studied intensively for more than a decade. However the experimental determination of the bonding geometry between the molecule and electrodes has remained elusive. Here we demonstrate by means of ab initio calculations that inelastic tunneling spectroscopy (IETS) can determine these geometries. We identify the bonding geometries at the gold-sulfur interfaces of propanedithiolate molecules bridging gold electrodes that give rise to the specific IETS signatures that were observed in recent experiments.