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O: Fachverband Oberflächenphysik

O 13: Organic Molecules on Inorganic Substrates: Adsorption and Growth

O 13.8: Vortrag

Montag, 17. März 2025, 16:45–17:00, H8

Reactions of benzoporphyrins with Cu(111) — •Maximilian Muth, Majid Shaker, Julien Steffen, Alexander Wolfram, Simon Steinbach, Andreas Görling, Hans-Peter Steinrück, and Ole Lytken — Friedrich-Alexande-Universität Erlangen-Nürnberg, Germany

Porphyrins are molecules with many interesting properties that change upon adsorption on solid substrates. This can lead to something as simple as a change in conformation of the molecule or something more drastic as a reaction with - or catalyzed by - the substrate. We have focused on three molecules: free-base tetraphenyl transdibenzoporpyhrin, copper tetraphenyl transdibenzoporpyhrin and free-base tetraphenyl tetrabenzoporpyhrin adsorbed on Cu(111). Using temperature-programmed desorption, X-ray photoelectron spectroscopy, scanning tunneling microscopy and density-functional theory calculations, we have identified three reactions in the temperature range from 280 to 1000 K. In the first reaction step at 350 - 480 K the free-base benzoporphyrins react with copper atoms from the substrate, forming metalloporphyrins. At 480 - 650 K, the phenyl rings and pyrrole/benzo rings undergo a ring fusion reaction. Finally, at 650 - 950 K, the molecules polymerize and all remaining hydrogen atoms desorb from the surface as H2.

Keywords: Porphyrins; Copper; TPD; XPS; STM