Gold Clusters Sliding on Graphite: a Possible Quartz Crystal Microbalance Experiment?

TL;DR

This paper explores the potential of using Quartz Crystal Microbalance to measure the phononic sliding friction of gold nanoclusters on graphite, predicting measurable slip times and the possibility of observing melting phenomena through frictional changes.

Contribution

It proposes a novel experimental approach to measure nanocluster friction and predicts measurable slip times at specific temperatures, linking frictional behavior to melting.

Findings

Predicted slip times around 10^(-9) seconds at 450-500 K.

QCM could detect melting of gold nanoclusters via frictional changes.

The approach connects diffusion data with friction measurements.

Abstract

A large measured 2D diffusion coefficient of gold nanoclusters on graphite has been known experimentally and theoretically for about a decade. When subjected to a lateral force, these clusters should slide with an amount of friction that could be measured. We examine the hypothetical possibility to measure by Quartz Crystal Microbalance (QCM) the phononic sliding friction of gold clusters in the size range around 250 atoms on a graphite substrate between 300 and 600 K. Assuming the validity of Einstein's relations of ordinary Brownian motion and making use of the experimentally available activated behavior of the diffusion coefficients, we can predict the sliding friction and slip times as a function of temperature. It is found that a prototypical deposited gold cluster could yield slip times in the standard measurable size of 10^(-9) sec for temperatures around 450-500 K, or 200 C. Since gold nanoclusters may also melt around these temperatures, QCM would offer the additional chance to observe this phenomenon through a frictional change.