Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 18: Organic Thin Films I
DS 18.4: Talk
Wednesday, April 2, 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).