Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Organic Molecules on Inorganic Substrates I: Adsorption & Growth

O 6.4: Talk

Monday, March 18, 2024, 11:15–11:30, MA 042

Identifying the Surface Arrangement of a Mixed Zinc Tetraphenylporhyrin and Monocarboxyphenyl Triphenylporphyrin Layer on Rutile TiO2(110) Using XPS — •Maximilian Muth, Alexander Wolfram, Hans-Peter Steinrück, and Ole Lytken — Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

Gaining deeper knowledge about the adsorption behavior of organic molecules on substrate surfaces is crucial for possible applications. One approach to learn about the (relative) adsorption strength of different molecules is to subsequently adsorb different molecules on top of each other at low temperature, and study the preferential displacement of the weaker bound species from the surface upon heating. Using this method, we have identified the relative adsorptions strengths of three tetraphenylporphyrins (ZnTPP, CoTPP, MgTPP) on rutile TiO2(110).[1] Moreover, we have recently addressed layers of these non-functionalized molecules and the carboxylic-acid-functionalized tetraphenylporphyrin (2HMCTPP), which is expected to bind more strongly to the surface. Interestingly, instead of completely displacing the non-functionalized molecules, we found 2HMCTPP to adsorb upright standing on free adsorption sites in between the flat-lying non-functionalized molecules.

[1] Muth et al., Accurate Determination of Adsorption-Energy Differences of Metalloporphyrins on Rutile TiO2(110) 1x1, Langmuir 2022, 38, 28, 8643-8650

Keywords: porphyrins; TiO2; co-adsorption; XPS