Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 47: Metal substrates: Adsorption of organic / bio molecules V
O 47.2: Vortrag
Mittwoch, 24. März 2010, 10:45–11:00, H36
Diffusion of phthalocyanine on Ag(100) investigated by STM — •Grazyna Antczak1,2 and Karina Morgenstern1 — 1Leibniz University, Hannover, Germany — 2University of Wroclaw, Wroclaw, Poland
Information about the thermal stability of phthalocyanine as well as how the molecule binds to surfaces are crucial in a bottom up approach to build molecular electronics. Phthalocyanine is already widely used in technology, for example in laser printers, CDs, colorants and so on. How do these organic molecules move over a surface? In contrast to the well studied diffusion of individual atoms, molecules exhibit more motional degrees of freedom that make their movement much more complicated. It is likely that concerted mechanisms will play an important role in their diffusion. Such concerted movements were already proven to be present for movement of close-packed metallic clusters. We have carried out a study of phthalocyanine motion on the Ag(100) surface in low-temperature scanning tunneling microscopy in the temperature range 50-80 K. We will show that phthalocyanine starts thermal movement over the surface at 55 K and follows an Arrhenius relation at least up to 80 K. From the Arrhenius plot of diffusivity the activation energy of 116 meV for the movement of single molecules was obtained. The prefactor of diffusivity will also be discussed.