Regensburg 2004 – wissenschaftliches Programm
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SYOH: Organic and Hybrid Systems for Future Electronics
SYOH 5: Poster
SYOH 5.83: Poster
Donnerstag, 11. März 2004, 18:00–21:00, B
Linewidth-limited energy transfer in single conjugated polymer molecules — •John Lupton1, Juergen Mueller1, Florian Schindler1, Ullrich Scherf2, and Jochen Feldmann1 — 1Photonics and Optoelectronics Group, Sektion Physik, LMU Muenchen — 2FB Chemie, Universitaet Wuppertal
Single molecule fluorescence spectroscopy is a powerful tool, which allows a direct distinction between homogeneous and inhomogeneous spectral broadening. We apply this technique to gain fundamental insight into energy transfer processes in conjugated polymers relevant to molecular electronics. At low temperatures we are able to identify individual homogeneously broadened chromophore units on the polymer chain. Using time resolved and polarisation sensitive fluorescence spectroscopy we image the intramolecular transfer of excitation energy from higher energy segments on the chain to lower energy segments. As the temperature is raised we find that the emission lines of individual chromophore units are broadened. Concomitantly, the average polarisation anisotropy decreases, suggesting that excitation energy is distributed across different chromophore units. Studies of the single chain fluorescence as a function of time show a pronounced blinking behaviour of the multichromophoric chain at room temperature, but not at low temperatures, demonstrating that chromophore coupling is controlled by temperature and spectral linewidth (Mueller et al., Phys. Rev. Lett. 2003). High resolution fluorescence spectroscopy also enables us to gain insight into the strength and nature of vibrational coupling and structural relaxation on a single molecule level.