Berlin 2014 – scientific programme

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MO: Fachverband Molekülphysik

MO 17: Excitons and Excitation Transfer (SYET 2)

MO 17.1: Invited Talk

Thursday, March 20, 2014, 14:00–14:30, BEBEL HS213

Non-adiabatic relaxation dynamics in perylene bisimide dimers excited by femtosecond laser pulses — •Volker Engel¹, Bernd Engels¹, Mirjam Falge¹, Martin Kess¹, Stefan Lochbrunner², Alexander Schubert¹, Volker Settels¹, Walter Strunz¹, and Frank Würthner³ — ¹Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Emil-Fischer- Str. 42, 97074 Würzburg, Germany — ²Institut für Physik, Universität Rostock, Universitätsplatz 3, 18055 Rostock, Germany — ³Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg

We present a model for the relaxation dynamics in perylene bisimide dimers which is based on ab-initio electronic structure and quantum dynamics calculations including effects of dissipation. The excited state dynamics proceeds via a mixing of electronic states of local Frenkel and charge-transfer characters which becomes effective upon a small distortion of the dimer geometry. In this way it is possible to explain the fast de-population of the photo-excited state as seen in femtosecond transient absorption measurements. This hints at a trapping mechanism which involves non-adiabatic and dissipative dynamics in an excited state vibronic manifold.