Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 32: Poster Session - Organic Molecules on Inorganic Substrates: Adsorption and Growth
O 32.6: Poster
Monday, March 16, 2020, 18:15–20:00, P1C
Investigation of the formation of densely packed 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-44221, Dortmund, Germany — 2DELTA, TU Dortmund, Maria-Goeppert-Mayer-Str. 2, D-44221, 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). Caffeine is well known for influencing the human central nervous system, therefore knowledge of the structural behaviour of caffeine is essential.
Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and x-ray photoelectron spectroscopy (XPD) have been used to examine the formation of caffeine on Au(111). In addition, density functional theory (DFT) calculations were carried out which allow conclusive interpretation as well as a comparison with the measured data.
We observed the caffeine molecules to be adsorbed in a quasi-hexagonal formation similar to the high-temperature α-phase, comprising two domains. The DFT calculations suggested a unit cell containing three molecules, the theoretically calculated structure is in excellent agreement to the experimental measured LEED and STM pattern, as well as to the measured XP-spectra. Furthermore, within the XPS measurements, no strong adsorbate-surface interaction was found.