SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 6: Poster Session I: Organic molecules on inorganic substrates: Adsorption and growth I
O 6.7: Poster
Montag, 1. März 2021, 10:30–12:30, P
Structural Investigation of Caffeine Monolayers on Au(111) — Malte G.H. Schulte1,2, Andreas Jeindl3, •Julian A. Hochhaus1, Ismail Baltaci1,2, Marie Schmitz1,2, Ulf Berges1,2, Oliver T. Hofmann3, and Carsten Westphal1,2 — 1Experimentelle Physik 1, TU Dortmund, Otto-Hahn-Str. 4, D-44227, Dortmund, Germany — 2DELTA, TU Dortmund, Maria-Goeppert-Mayer-Str. 2, D-44227, Dortmund, Germany — 3Institut für Festkörperphysik, NAWI Graz, Technische Universität Graz, Petersgasse 16, A-8010 Graz
In this study, we investigate caffeine monolayers on Au(111). The asymmetric and achiral structure of the caffeine molecule leads to two surface chiralities, which influence the crystal growth of caffeine. Knowledge of these structural properties is of interest because of the in- fluence of caffeine on the human central nervous system.
Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS) were used to determine the structure of adsorbed caffeine. Additionally performed density functional theory (DFT) calculations allowed a conclusive interpretation of the results. We observed that the caffeine molecules adsorbed in a quasi-hexagonal formation resembling the high-temperature α phase and comprising two domains. The DFT calculations suggest a unit cell containing three molecules. The theoretically calculated structure is in excellent agreement with the experimentally measured LEED, STM and XPS data. The results are published in Phys. Rev. B 101, 245414 (2020).