Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Metal substrates: Adsorption of organic / bio molecules V

O 37.8: Talk

Wednesday, March 25, 2009, 16:45–17:00, SCH A118

Theoretical investigation of the adsorption of dithiolates on Au surfaces — •Katrin Tonigold and Axel Groß — Institute for Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany

Thiolates are one of the most commonly used anchor groups of molecules that form self assembled monolayers (SAMs), as they yield stable monolayers because of the strong Au-S-interaction. An even higher stability should be expected if disulfide-containing anchor groups are used. Such groups are bigger than single thiolates and might lead to different structures on the surface that could be used as a new type of template for surface reactions.

In cooperation with experimentalists from the chair of Physical Chemistry I at the Ruhr-University Bochum, the adsorption of 1,2-dithiolan species and related α,γ-dithiolates has been investigated by means of DFT-GGA-calculations. In order to understand the molecule-surface interaction, the electronic structure of the most stable adsorption configurations at different coverages has been analyzed. Furthermore, the effect of different rest groups attached to disulfide-containing anchor groups has been examined. Weak van der Waals forces between these rests were taken into account via post-Hartree-Fock calculations of molecular pairs in the gas phase.

Additionally, as there are both experimental and calculational hints [1] that thiolate adsorption on Au can induce surface rearrangements, the influence of defects on the molecule-surface interaction has been considered.
[1] P. Maksymovych et al., Phys. Rev. Lett. 97, 146103 (2006).