Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 109: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures VII

O 109.1: Talk

Friday, March 16, 2018, 10:30–10:45, MA 004

Insight into the unit cell: Structure of picene thin films on Ag(100) revealed with complementary methods — •Tobias Huempfner, Martin Hafermann, Christian Udhardt, Felix Otto, Roman Forker, and Torsten Fritz — Friedrich Schiller University, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena, Germany

We studied the molecular structure of one monolayer of picene on a Ag(100) surface. Low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) experiments show that the molecules arrange in a highly ordered manner exhibiting a point-on-line epitaxy with two differently arranged molecules per unit cell. Besides the structural investigations, we also studied the electronic properties via photoelectron spectroscopy. In particular, we recorded photoelectron momentum maps (PMMs) at different binding energies. PMMs based on molecular orbitals obtained from density functional theory (DFT) calculations of free molecules are simulated for a better understanding of the measured maps. Comparing measured and simulated PMMs allows further conclusions about the composition of the unit cell. The structural basis consists of two parallel molecules; one molecule lies face-on and the other is tilted by 45° around its long axis with respect to the surface normal.