Hamburg 2009 – scientific programme
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MO: Fachverband Molekülphysik
MO 24: Elektronische Spektroskopie
MO 24.2: Talk
Friday, March 6, 2009, 11:00–11:15, VMP 6 HS-G
Photoblinking of single calix[4]arene-based perylene bisimide dimers — •Dominique Ernst1, Richard Hildner1, Catharina Hippius2, Frank Würthner2, and Jürgen Köhler1 — 1Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany — 2Institut für Organische Chemie, Universität Würzburg, 97074 Würzburg, Germany
We present how the photoblinking behaviour of single bridge-linked perylene bisimide dimers is exploited to investigate the influence of subtle conformational variations on the efficiency of energy transfer processes within these assemblies. The molecular structure of the dimer gives rise to a weak electronic coupling between its subunits. By using fluorescence spectroscopy we observed photodegradation and blinking over three decades in time scale. Statistical analysis of the photoblinking dynamics revealed a typical power-law distribution for the off-times with exponents of md=−1.9 and mm=−1.8 for the dimer-level and monomer-level, respectively. This observation, which is typical for single-molecules embedded in polymer matrices, is interpreted by electron tunneling processes from one of the dimer chromophores to the surrounding matrix and subsequent excitation-energy transfer from the other chromophore to the radical, resulting in fluorescence quenching. The observed intensity time-traces could be grouped into three categories, which were assigned to different mutual orientations and distances of the subunits. Finally we propose a simple model that explains the time-traces of the individual dimers qualitatively.