Single molecule studies of electronic excitation energy transfer: From simple model systems to conjugated polymers
Prof. Dr. Thomas Basché (Institut für Physikalische Chemie, Universität Mainz)

<p> Electronic Excitation Energy Transfer plays a key role the functioning of natural light-harvesting complexes and light-emitting devices composed of conjugated polymers. As has been shown in recent years, single molecule spectroscopy gives novel insights into the fundamentals of electronic excitation energy transfer in molecular aggregates. In order of increasing structural complexity we have studied simple molecular dimers, multichromophoric dendrimers and (conjugated) polymers [1, 2]. It will be shown that the combination of frequency selective single molecule spectroscopy and confocal fluorescence microscopy at 1.4 K is a unique tool to study energy transfer processes in these systems. In particular, from the line widths of single molecule excitation spectra rate constants of energy transfer can be deduced directly. A detailed analysis shows that for several cases the mechanism of energy transfer cannot be described by the simple Förster model (dipole-dipole coupling). Furthermore, novel experiments with dual color pulsed excitation will be presented which allow for controlling the excitation energy flow in individual molecular dimers [3]. <p>

<p> [1] R. Metivier, F. Nolde, K. Müllen, Th. Basché, Phys. Rev. Lett. 98 (2007) 047802. <p>

<p> [2] F. Feist, G. Tommaseo, Th. Basché, Phys. Rev. Lett. 98 (2007) 208301. <p> <p> [3] B. Fückel, G. Hinze, F. Nolde, K. Müllen, Th. Basché, Phys. Rev. Lett. 103 (2009) 103003. <p>