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Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 35: Single molecules I

CPP 35.5: Talk

Wednesday, March 9, 2005, 10:45–11:00, TU C243

Electrothermal manipulation of single chromophores in PI-conjugated polymers — •Florian Schindler1, John M. Lupton1, Jochen Feldmann1, and Ullrich Scherf21Photonics and Optoelectronics Group, Department of Physics, LMU Munich — 2FB Chemie, University of Wuppertal

Single molecule spectroscopy and imaging is an excellent tool for studying optoelectronics on a molecular scale. With this technique we are able to identify single chromophores on an electroluminescent ladder-type poly(para-phenylene) molecule at low temperatures [1] and observe random changes of the emission frequency of single chromophores due to spectral diffusion [2]. By exposing single molecules placed on top of tiny conducting strip lines to short electrically generated heat pulses we initiate an abrupt increase of the linewidth during the pulse followed by a subsequent reduction. Furthermore, we observe a random jump of the emission frequency. These spectral jumps span over almost the entire range of the inhomogeneously broadened ensemble spectra indicating changes in the chromophore surrounding and its position within the polymer backbone. Depending on the polymer chain length, we can also identify an off/on switching of the fluorescence following the heat pulse. This is due to efficient energy transfer to trap sites [1].
Müller et al., PRL 91, 267403 (2003)
Schindler et al., PNAS 101, 14695 (2004)

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