Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 40: Surface Dynamics

O 40.4: Talk

Tuesday, March 18, 2025, 14:45–15:00, H6

Controlled formation of thermodynamically unaccessible surface structures — •Simon B. Hollweger, Anna Werkovits, and Oliver T. Hofmann — Institute of Solid State Physics, Graz University of Technology, Austria

It is well known that organic molecules adsorbed on surfaces can form a variety of different surface structures. Which structure is the most favored one at a given temperature and pressure is determined by thermodynamics. However, in this study, we propose the idea of a mechanism with which we can control the formation of a specific metastable surface polymorph that can not be reached thermodynamically. With targeted temperature and pressure changes, a rearrangement process of the adsorbed molecules out of thermodynamic equilibrium is triggered. For specifically designed systems, this rearrangement of the adsorbed molecules leads to a kinetically trapped metastable surface polymorph. As a proof of principle for this proposed mechanism, kinetic Monte Carlo simulations of planar molecules adsorbing on a square lattice are conducted. We show that a metastable upright-standing structure of the planar molecules can be reached with a specific temperature and pressure profile applied to the system.

Keywords: metastability; kinetic monte carlo; microkinetic simulation; surface kinetics; phase transition