Berlin 2005 – scientific programme

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MO: Molekülphysik

MO 43: Ultrafast Processes

MO 43.2: Talk

Tuesday, March 8, 2005, 16:45–17:00, HU 2091

Ultrafast emission quenching due to charge transfer from the perylene bisimide chromophore to its substituent — •Patrizia Krok¹, Ida Z. Kozma¹, Stefan Lochbrunner¹, Heinz Langhals², and Eberhard Riedle¹ — ¹LS für BioMolekulare Optik, Ludwig-Maxilimians-Universität München — ²Department Chemie, Organische Chemie, Ludwig-Maxilimians-Universität München

Perylene dyes can exhibit a fluorescence quantum yield of 100% due to vanishing internal conversion and intersystem crossing. At the same time they are of great interest for designing ultrafast intramolecular energy and charge transfer systems [1,2]. Their functionality is controlled by the specific substituents and the environment. An amino group can act as an acceptor resulting in strong fluorescence suppression [3]. We measure with a femtosecond visible continuum the transient emission and absorption after excitation by 30 fs pulses at 490 nm to gain insight into the intramolecular transfer dynamics. We compare the emission decay of the amino substituted perylene chromophore on the picosecond time scale to the ns decay in the case of a nonquenching substituent. It can be explained by electron transfer from the HOMO of the amino group to the chromophore. The back transfer proceeds in about 10 ps and makes the whole reaction cycle highly efficient.

[1] H. Langhals, Heterocycles 40, 477 (1995). [2] H. Langhals and S. Saulich, Chem. Eur. J. 8, 5630 (2002). [3] G. J. Mohr et al., Anal. Chem. 72, 1084 (2000).