Dynamic scanning probe microscopy of adsorbed molecules on graphite

TL;DR

This study demonstrates the use of dynamic scanning probe microscopy techniques to image and analyze weakly bound molecules on graphite, revealing molecular organization and weak interactions through imaging and spectroscopy.

Contribution

It introduces combined dynamic STM/AFM methods for imaging weakly adsorbed molecules with molecular resolution and confirms weak molecule-substrate interactions via tunneling spectroscopy.

Findings

Molecular resolution achieved in dynamic STM imaging.

Weak molecule-substrate interactions confirmed by energy gap measurements.

Imaging mode similar to conventional STM demonstrated.

Abstract

We have used a combined dynamic scanning tunneling and atomic force microscope to study the organisation of weakly bound adsorbed molecules on a graphite substrate. Specifically we have acquired images of islands of the perylene derivative molecules. These weakly bound molecules may be imaged in dynamic STM, in which the probe is oscillated above the surface. We show that molecular resolution may be readily attained and that a similar mode of imaging may be realised using conventional STM arrangement. We also show, using tunnelling spectroscopy, the presence of an energy gap for the adsorbed molecules confirming a weak molecule-substrate interaction.