STM and STS of coronene on HOPG 0001 in UHV - adsorption of the smallest possible graphite flakes on graphite.
The adsorption of the aromatic molecule hexabenzobenzene (coronene) on an HOPG(0001) surface was investigated under UHV conditions by means of variable temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Imaging on a mesoscopic scale showed a distribution of coronene islands. These islands are mobile on the surface and can be pinned at step-edges. Zooming in on areas apart from the islands reveals an hexagonal arrangement of coronene molecules in a closed layer. Submolecular resolved molecules consist of bright spots with varying intensity. This variation in intensity is explained with the commensurability of the adlayer. STS investigations were performed for various tip-sample distances, adjusted by the tunneling current setpoint. A gap can be seen for every setpoint, but its width is dependent on the setpoint. The gap for the largest tip-sample distance and therefore the smallest tip-sample interaction is compared with the theoretical value.
Lackinger
Markus
M
Chemnitz University of Technology, Institute of Physics, Reichenhainer Str 70, 09107 Chemnitz, Germany. markus.lackinger@physik.tu-chemnitz.de
Griessl
Stefan
S
Heckl
Wolfgang M
WM
Hietschold
Michael
M