Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 47: Metal substrates: Adsorption of organic / bio molecules V

O 47.8: Talk

Wednesday, March 24, 2010, 12:15–12:30, H36

SnPc on Ag(111) investigated by STM — •Christoph Kleimann, Ingo Kröger, Christian Weiss, Christa Elsaesser, and Christian Kumpf — Institut für Bio- und Nanosysteme (IBN3), FZ Jülich & JARA-FIT

The investigation of interfaces between thin organic films and metal surfaces is a field of highest interest because it represents the basis for future applications of organic electronic devices. In this context, phtalocyanines are of particular interest since repulsive intermolecular interaction was found recently for this group of organic molecules [1]. Tin(II)-phtalocyanine (SnPc) is non-planar and can adsorb in two different geometries: with the Sn atom pointing downwards (Sn down) or upwards (Sn up). In our group different Pc molecules have previously been studied using several experimental techniques like SPA-LEED or XSW (see also contributions by I. Kröger and B. Stadtmüller). Here we present STM studies of SnPc on Ag(111), taken at different coverages and temperatures, and discuss the results in the context of our previous findings. At low coverages the formation of chains can be observed for Sn down molecules while Sn up molecules tend to stay separated. This originates from a strong interaction with the substrate which leads to a broken symmetry of the SnPc molecules. Measurements at higher coverages show large ordered areas of Sn down molecules which are oriented along the different domains of the silver surface. The combination of STM and LEED in our setup allows to precisely correct the STM images for distortions and therefore enables a quantitative analysis of the adsorption geometry. [1] Nat. Phys. 5, pp 153-158 (2009)