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O: Fachverband Oberflächenphysik
O 6: Organic/bio Molecules on Metal Surfaces I
O 6.10: Talk
Monday, March 11, 2013, 12:45–13:00, H38
Temperature influence on the self-assembly of phthalocyaninato complexes on gold studied by second harmonic generation (SHG). — •Nadezhda Lilichenko1, Ulrich Glebe2, Frank Hubenthal1, Ulrich Siemeling2, and Frank Träger1 — 1Institut für Physik, Universität Kassel and CINSaT, Germany — 2Institut für Chemie, Universität Kassel and CINSaT, Germany
Self assembled monolayers (SAMs) attracted great attention in different fields of science. Due to their designable physical and chemical properties SAMs are used in a variety of applications, e.g. as biosensors, switchable interfaces or in molecular electronics. Phthalocyanines (Pcs) are ideal candidates for SAMs due to their outstanding optical and electronic properties.These molecules bind to the surface by multiple anchor groups and they have large footprints, which are preconditions for the formation of stable monolayers. In our experiments we have used thioether substituted (sub-)phthalocyanines for SAM formation. To extract the adsorption kinetics the film formation was monitored by optical second harmonic generation and subsequently the SHG data was fitted by the standard Lamgmuir kinetic models. Depending on the molecular structure, the adsorption can be described either by 1st or 2nd order Langmuir kinetic models. Additionally, the temperature and the molecular concentration of the Pc-solution has been systematically varied to optimise SAM formation. The most important result, among other, is, a strong dependence on the temperature. While for T = 2∘C the SAMs were only loosely packed, at T = 25∘C dense films are generated.