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DS: Fachverband Dünne Schichten

DS 46: Organic Thin Films III

DS 46.2: Vortrag

Freitag, 26. März 2010, 14:15–14:30, H8

Luminescence of PTCDA monolayers on NaCl in relation to their structural properties — •Mathias Müller, Eric Le Moal, Oliver Bauer, and Moritz Sokolowski — Institut für Physikalische u. Theoretische Chemie, Universität Bonn, Wegelerstraße 12, 53115 Bonn

On insulating surfaces the luminescence of monolayers of organic molecules can be studied in detail whereas on metals the luminescence is suppressed in most cases. The use of thin epitaxial NaCl(100) films grown on Ag(100) enabled us to perform spot profile analysis-LEED parallel to in-situ photoluminescence spectroscopy. Under optimized evaporation conditions we obtain different PTCDA monolayer structures, namely a commensurate 3x3 superstructure, an incommensurate herringbone-structure, and a disordered phase. All phases have interesting photoluminesce properties with sharp peaks and a well resolved vibronic finestructure in common. Besides, their luminescence spectra differ significantly in their energetic positions. Calculations based on a point-dipole model show that the corresponding exciton band structures have to be described by J-aggregates. This allows to explain the observed energetic differences of the luminescence spectra of these phases in detail. Funding by DFG research unit 557 is gratefully acknowledged.