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O: Fachverband Oberflächenphysik

O 44: Focussed session: Functional molecules at surfaces II

O 44.4: Vortrag

Mittwoch, 28. März 2012, 11:45–12:00, A 053

Thermally induced switching of azobenzene at coinage metal surfaces? A DFT perspective — •Reinhard J. Maurer and Karsten Reuter — TU München

Stimulating a controlled isomerization of functional molecules stabilized at a solid surface is a central step en route to a future molecular nanotechnology. Central questions particularly at metal substrates concern the detailed excitation mechanism and in how much established gas-phase isomerization pathways are modified by the presence of the surface. Building the basis for a detailed understanding of photo-induced isomerization we use dispersion-corrected density-functional theory to investigate the thermal switching of the prototypical molecular switch azobenzene at Au(111). For this we compute energy profiles for isomerization mechanisms predominantly discussed in gas-phase and analyze the electronic structure along the way. We find that the interaction with the surface selectively favors the rotational against the inversion pathway, and thereby reverses the ordering established in gas-phase or solution. Extending our calculations to Ag(111) surfaces as well as to tetra-tert-butyl-azobenzene (TBA) we specifically target the role of the substrate d-band and the influence of functional groups.