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DS: Fachverband Dünne Schichten

DS 18: Organic Thin Films I

DS 18.4: Vortrag

Mittwoch, 2. April 2014, 10:15–10:30, CHE 91

Investigation of Rubrene Thin Films on Graphite — •Christian Udhardt¹, Yu Watanabe², Takashi Yamada², Roman Forker¹, Toshiaki Munakata², and Torsten Fritz¹ — ¹Friedrich Schiller University, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena, Germany — ²Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan

The aim of our present work is to localize electronic states on organic thin film surfaces and associate them with film structures. The object of study is a graphite surface covered with rubrene (C₄₂H₂₈), an organic dye from the class of polycyclic aromatic hydrocarbons (PAH). Previous studies of the graphite/rubrene interface with two-photon photoemission spectroscopy (2PPES) showed an enhanced, resonant excitation of a specific, unoccupied molecular orbital, which was labeled as Ln [J. Phys. Chem. C 116, 5821 (2012)]. It is expected that the properties of the Ln excitation are influenced by an interaction with the image potential state of the graphite surface (IPS1). In this study, photoemission electron microscopy (PEEM) was used to localize the Ln excitation on the sample surface and gather further confirmations of the Ln-IPS mixing. Photon energy as well as film thickness dependence was investigated. In addition, the crystal structure at different thicknesses was characterized with low energy electron diffraction (LEED) and the light absorption behavior of the rubrene films was elucidated with differential reflectance spectroscopy (DRS).