Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Metal Substrates: Structure, Epitaxy and Growth

O 44.1: Poster

Tuesday, March 21, 2017, 18:30–20:30, P1A

On the Thin Film Growth of Two Isomers of Dibenzopentacene on Ag(111) — •Tobias Huempfner, Lennart Vorbrink, Felix Otto, Maximilian Schaal, Bernd Schroeter, Roman Forker, and Torsten Fritz — Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany

We report on the thin film growth of two isomers of the molecule dibenzopentacene (DBPen) deposited on a Ag(111) surface. The different molecular configurations, namely 1,2:8,9-DBPen (trans) and 1,2:10,11-DBPen (cis), differ only in the position of one of the additional benzene rings relative to the pentacene backbone. The optical properties during the growth were measured via differential reflectance spectroscopy (DRS) and interpreted by comparing to calculated excitation spectra obtained from time-dependent density functional theory (TD-DFT) of the isolated molecule. Furthermore, the films were characterized structurally via low-energy electron diffraction (LEED) and low-temperature scanning tunneling microscopy (STM) for different film thicknesses. While the optical properties of the two isomers hardly differ in the visible region, the structural properties vary significantly. The first monolayer of the trans-isomer grows in a highly ordered structure. In contrast, for the monolayer of cis-DBPen no well-defined adlayer exhibiting translational order was observed, although first-order LEED-spots occur owing to the preferential molecular alignment with the substrate.