Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 85: Metal substrates: Adsorption of organic / bio molecules VII
O 85.5: Vortrag
Freitag, 26. März 2010, 12:15–12:30, H36
Conformational switching of porphyrin derivatives on Au(111) by heating and STM manipulation — •Johannes Mielke1,2, Matthew Dyer3, Mats Persson3, Stefan Hecht4, Jesús Martinez-Blanco2, Karsten Horn2, and Leonhard Grill1,2 — 1Institut für Experimentalphysik, Freie Universität Berlin — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin — 3Department of Chemistry, University of Liverpool, United Kingdom — 4Institut für Chemie, Humboldt-Universität zu Berlin
Molecular switches, which exhibit at least two stable states with characteristic properties, could play an important role in future applications of molecular electronics for the control of the conductance or the implementation of logic functions. Although such molecules have been investigated intensely in solution, the knowledge about their switching properties when being adsorbed on a solid surface is still scarce. We have studied functionalised porphyrin molecules on a Au(111) surface at different temperatures. In STM images, two stable conformations can be distinguished by their characteristic appearance. When applying voltage pulses with the STM tip to single molecules at low temperatures (around 7 K), it is possible to switch the molecules reversibly from one conformation to the other, whereas the voltage thresholds turn out to be characteristic. On the other hand, thermal switching is observed at elevated temperatures of around 300 K. The high number of switching events in the regime of thermal switching can be used to gain detailed insight in the dependence of the switching process on the atomic-scale environment of the molecule.