Hannover 2013 – scientific programme
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MO: Fachverband Molekülphysik
MO 28: Photochemistry
MO 28.5: Talk
Friday, March 22, 2013, 12:15–12:30, F 102
An organic photochromic triad acting as optical gate — •Martti Pärs1, Michael Gradmann1, Regina Schmidt1, Katja Gräf2, Peter Bauer2, Mukundan Thelakkat2, and Jürgen Köhler1 — 1Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany — 2Applied Functional Polymers, University of Bayreuth, 95440 Bayreuth, Germany
We demonstrate optical modulation experiments with an organic photoswitchable triad. The triad consists of a photochromic unit (dithienylcyclopentene, DCP) that can be interconverted between two bistable (open and closed) forms by light, and two highly efficient fluorophores (perylenebisimide, PBI).[1] Fluorescence microscopy reveals that the DCP features a highly efficient photoreaction which can be probed via the fluorescence change of the PBI unit. Conversion the DCP unit by visible and UV radiation, results in a reversible strong modulation of the fluorescence intensity of the PBI. Hence the DCP unit acts as a gate (triggered by a few photons), that controls the flow of many fluorescence photons from the PBI unit. We will present a model that describes the experimental observations, such as the fluorescence modulation contrast ratio, the reaction rates and the reaction quantum yields as a function of radiation intensities.
[1] M. Pärs, C.C. Hofmann, K. Willinger, P. Bauer, M. Thelakkat, J. Köhler, Angew. Chem. Int. Ed. 2011, 50, 11405-11408