Epitaxial growth of C$_{60}$ on highly oriented pyrolytic graphite surfaces studied at low temperatures

TL;DR

This study uses low-temperature STM to investigate the epitaxial growth and molecular self-assembly of C60 on highly oriented pyrolytic graphite, revealing island growth modes and specific epitaxial orientations.

Contribution

It provides detailed atomic-scale insights into the epitaxial relationships and growth modes of C60 molecules on HOPG surfaces at low temperatures.

Findings

Confirmed island growth mode of C60 on HOPG

Identified three possible epitaxial orientations

Determined specific epitaxial relationship through high-resolution imaging

Abstract

Graphite surfaces interact weakly with molecules compared to other conducting surfaces bringing the molecule-molecule interaction to the foreground. C$_{60}$ on highly oriented pyrolytic graphite is a model system for studying the molecular self-assembly on surfaces. Our scanning tunneling microscopy measurements at liquid nitrogen temperatures confirm the previously observed island growth mode. Our results indicate that there is an epitaxial relationship of the molecular islands and the substrate with three possible orientations of the islands. For one of these orientations, we determine this epitaxial relationship by analyzing in detail an image taken across a C$_{60}$ island step edge. In this image we have obtained high resolution on both the molecular island and the substrate. The result of this analysis is confirmed by two-dimensional Fourier analysis.