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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.28: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

Luminescence of PTCDA on epitaxial KCl films on Ag(100) — M. Müller, •A. Paulheim, C. Marquardt, and M. Sokolowski — Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstraße 12, 53115 Bonn, Germany

On surfaces of the wide gap dielectric materials the luminescence of organic molecules can be studied in great detail. Thin films of the molecule perylence-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) were vacuum deposited on epitaxial KCl films on Ag(100). The structural and optical properties were investigated by spot-profile-analysis low energy electron diffraction (SPA-LEED) and by photoluminescence- (PL) and PL excitation spectroscopy (PLE). We investigated molecules in the limit of isolated entities and of a completed monolayer. The SPA-LEED measurements reveal the know quadratic unit cell of the monolayer with the molecules arranged in a brickwall-structure [1]. The optical spectra exhibit a dominating 0-0 transition and well resolved vibronic modes. The transition energy of molecules embedded in a completed monolayer phase is redshifted with respect to that of isolated molecules. In addition, we analyzed the polarization of the emitted light and were able to determine the azimuthal orientation of the organic molecules in both phases with respect to the KCl(100) surface. From these data we achieve detailed information on the role of the intermolecular coupling on the optical properties of the layers. Supported by the DFG through the research group 557. [1] T. Dienel, C. Loppacher, S. C. B. Mannsfeld, R. Forker, and T. Fritz, Advanced Materials 20, 959 (2008)