Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 74: Organic Molecules at Surfaces 5: Molecular Switches

O 74.3: Vortrag

Donnerstag, 8. September 2022, 15:30–15:45, S054

Precise control of single-molecule motion on Ag(111) — •Donato Civita, Grant Simpson, and Leonhard Grill — Department of Physical Chemistry, University of Graz, Austria

The motion of molecules adsorbed on metal single crystal surfaces is of fundamental importance in various fields such as heterogeneous catalysis, and on-surface polymerization. During diffusion, however, the motion of adsorbed molecules is characterised by random direction changes and thus control is limited. Moreover, adsorbates in the surroundings as well as substrate defects can strongly influence molecular motion.

With the use of a scanning tunnelling microscope (STM) at low temperature, we can control the motion of single di-bromo-ter-fluorene (DBTF) molecules on a Ag(111) surface over distances of more than 100 nm with picometric precision [1]. We find that a single molecule can move strictly along one atomic row across the surface. The molecule can be repelled or attracted by the STM tip, driven by an interplay of van der Waals and electrostatic interactions. The large spatial extension of the motion, and its unidimensional confinement allow the direct measurement of the molecular velocity. Ultimately, this system demonstrates the possibility of studying the influence of surrounding adsorbates, crystal defects, and STM tip on the molecular motion and velocity.

[1] D. Civita, M. Kolmer, G. J. Simpson, A.-P. Li, S. Hecht, L. Grill, Control of long-distance motion of single molecules on a surface, Science, Vol. 370, Issue 6519, pp. 957-960 (2020).