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O: Fachverband Oberflächenphysik

O 34: Poster Session III: Organic molecules on inorganic substrates: Adsorption and growth III

O 34.1: Poster

Tuesday, March 2, 2021, 10:30–12:30, P

Elucidating the bonding of 2-mercaptobenzimidazole on Cu(111) by STM and DFT — •Marion A. van Midden, Matic Lozinšek, Tone Kokalj, and Erik Zupanič — Jožef Stefan Institute, Ljubljana, Slovenia

While organic corrosion inhibitors such as 2-mercaptobenzimidazole are widely used to protect the surface of copper, their bonding mechanism on the atomic scale remains elusive. DFT calculations have shown that different bonding configurations have comparable energies when considering the binding of a single molecule to the surface. In the case of larger coverages, which are common in real-life applications, various inter-molecular interactions have to be considered as well, further complicating calculations. To determine which interactions are most significant for the bonding and self-assembly of 2-mercaptobenzimidazole on the surface of Cu(111) we prepared samples in ultra high vacuum and imaged them using STM. Varying the evaporation rate and time as well as the substrate temperature allowed us to control the coverage and limit the energy the molecules have available to self assemble. Surprisingly the molecules formed ordered self-assembled structures even when depositing on samples cooled to approximately 50 K. These structures reassembled at temperatures below 100 K. Similarly, most of the observed structures rearranged when slightly heated. This opposes the idea that strong binding to specific sites on the surface is crucial for corrosion prevention. The large variety of obtained self-assembled structures at different deposition parameters suggests, that the energy scales of competing interactions must be similar.