Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Focussed session: Functional molecules at surfaces II

O 44.8: Talk

Wednesday, March 28, 2012, 12:45–13:00, A 053

Quantum chemical calculations and open-system density matrix simulations for arrays of molecular switches on surfaces — Gereon Floß, Manuel Utecht, •Tillmann Klamroth, and Peter Saalfrank — Theoretische Chemie, Universität Potsdam, Germany

In this work different models are investigated to describe the absorption spectra and excitonic coupling in self-assembled monolayers of azobenzenes, on the (TD-) B3LYP/6-31G* level of theory [1]. The calculated blue shifts in optical absorption spectra account for the experimental observations made for azobenzene/gold SAMs, and hint to the fact that they can indeed be responsible for reduced switching probability in densely packed self-assembled structures [2].

Furthermore, using a quite general open-system density matrix model, we demonstrate that nevertheless controlled and complete switching should be possible in arrays of molecular switches on surfaces by analytical and optimal control pulses and the concept of "laser distillation" [3]. The parameters for this dynamics model are chosen to roughly resemble the all-trans → all-cis isomerization of an array of azobenzene molecules on a surface.

[1] M. Utecht, T. Klamroth, P. Saalfrank, Phys. Chem. Chem. Phys. 13, 21608 (2011).

[2] C. Gahl, R. Schmidt, D. Brete, E. McNellis, W. Freyer, R. Carley, K. Reuter, M. Weinelt, J. Am. Chem. Soc., 132, 1831 (2010).

[3] G. Floß, T. Klamroth, P. Saalfrank, Phys. Rev. B 83, 104301 (2011).