Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 20: Solid / liquid interfaces II

O 20.2: Talk

Monday, March 14, 2011, 17:30–17:45, WIL B321

Influence of the substrate on the chemical state of adsorbed organic molecules: A XPS-study — •Stephan Breuer¹, Thanh-hai Phan¹, Mayer Thomas², Broekmann Peter³, and Wandelt Klaus^1,4,5 — ¹University of Bonn, Institute of Physical and Theoretical Chemistry, Wegelerstr. 12, D-53115 Bonn — ²Technical University of Darmstadt, Department of Material Science — ³Universtity of Berne, Department of Chemistry and Biochemistry — ⁴University of Wroclaw, Institute of Experimental Physics, Poland — ⁵University of Rome "Tor Vergata", Department of Physics, Italy

The template effect of an ordered surface and the self assembly of organic molecules due to their intermolecular interactions allow the formation of nano-structures in a bottom-up approach. We work in an aqueous solution which allows the deposition of thermolabile molecules. An electrochemical environment allows applying an electrical potential in order to change the redox state of organic adsorbates which in turn influences their intermolecular interactions. We have studied the adsorption of redox active organic molecules (e.g. viologens and porphyrins) on copper surfaces which are precovered with specifically adsorbed anions. The organic molecules are adsorbed as cationic moieties which bind electrostatically to the anion layer. Changes in the redox state influence their self-assembly behaviour. In this study we will show our characterization of the chemical and redox state of viologens on Cu(111) precovered with sulphide compared to former results on chloride precovered Cu(100) [1].

[1] St. Breuer et al., N. J. Phys, 10, 2008, 125033 (24pp.).