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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 63: Polymer and Molecular Dynamics II
CPP 63.3: Talk
Thursday, March 15, 2018, 10:00–10:15, C 264
Probing intramolecular energy transfer rates on the single molecule level — •Jakob Schedlbauer1, Philipp Wilhelm1, Florian Hinderer2, Sigurd Höger2, Jan Vogelsang1, and John M. Lupton1 — 1Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany — 2Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
Efficient excitation energy transfer (EET) is a key process in organic photovoltaic devices as well as in natural light harvesting complexes. Single molecule spectroscopy (SMS) has proved itself to be a powerful technique to probe the interactions between single isolated units or to visualize intramolecular energy migration. However, these EET processes take place on a timescale of a few picoseconds or even faster, which exceeds the temporal resolution of conventional SMS techniques. Here we present a new experimental approach to determine EET rates in a donor-acceptor-system on a single molecule level by influencing the photon statistic in a pump-pump like experiment. We excite the donor repetitively with a laser pulse train consisting of two pulses identical in terms of wavelength, polarization and power, separated by a variable time delay. After an excitation in the first pulse the donor moiety can only absorb a photon in the second pulse if it has decayed into the ground state by transferring its excitation energy to the acceptor. Using the technique of time correlated single photon counting (TCSPC) we can measure the probability for such a double excitation of our donor-acceptor system as a function of the time delay between the two pulses and therefore get access to the EET time constant.