Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 33: Epitaxie und Wachstum (II)

O 33.12: Vortrag

Donnerstag, 14. März 2002, 18:15–18:30, H44

Complex 2D Phase Behavior observed for Binary Mixtures of Porphyrin Derivatives — •Michael de Wild¹, Simon Berner¹, Hitoshi Suzuki², Thomas Jung³, and Hans-Joachim Guentherodt¹ — ¹Institute of Physics, University of Basel, Switzerland — ²Kansai Adv. Res. Ctr., Commun. Res. Lab.,Kobe, Japan — ³Paul Scherrer Institute, Switzerland

In our study, a variety of porphyrins and tetra-trimethylsilyl-Perylenes have been sublimed onto atomically clean Ag substrates of (100) and (111) orientation in ultra high vacuum. After deposition of one compound, these molecules often show a dynamic equilibrium of condensed 2D superstructure islands and 2D gas phases when observed by Scanning Tunneling Microscopy at room temperature (S. Berner, M. Brunner, L. Ramoino, H. Suzuki, H.-J. Güntherodt, and T.A. Jung, CPL 348 (2001) 175-181.). After co-deposition of two compounds, intermixed phases have been observed in addition to the gas phase and the condensed mono-phases. Detailed series of experiments reveal a complex phase behavior which involves changes of the layer symmetry and the 2d molecular interconnection in dependence of the mixing ratio. In sub-molecular resolution STM micrographs, molecular orientation and nearest neighbor interlinking can be studied in detail. This system is of particular interest because of its many features of distinctive difference from the more common segregation.