Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 46: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 46.9: Poster

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

Thickness-dependent photoelectron spectroscopy study of 1,2;8,9-dibenzopentacene on Au(111) — •Maximilian Schaal, Felix Otto, Christian Udhardt, Bernd Schröter, Roman Forker, and Torsten Fritz — Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany

Alkali-metal-doped polycyclic aromatic hydrocarbons received broad attention as potential organic superconductors during the last years. A representative of this class is potassium-doped 1,2;8,9-dibenzo-pentacene (DBPen) which has a reported transition temperature of 33 K in bulk powder samples [1]. Here we investigate thin films of DBPen on Au(111) by means of thickness-dependent x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The XPS results show a thickness-independent line shape and an energy shift by the formation of an interface dipole. The UPS results show an asymmetric broadening of the highest occupied molecular orbital (HOMO) in the monolayer which is attributed to the occurrence of vibronic states. The HOMO splitting in the bilayer indicates the formation of a dimer structure via π-stacking. Furthermore, we explore the thickness-dependent modification of the binding energy and effective mass of the Shockley surface state of Au(111) by angle-resolved UPS (ARUPS).

[1] M. Xue et al., Sci. Rep. 2, 389 (2012).