Darmstadt 2008 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Femtosekundenspektroskopie II

MO 4.8: Vortrag

Montag, 10. März 2008, 18:15–18:30, 3G

Heterogeneous Electron Transfer Dynamics in Systematically Varied Perylene/TiO2 Systems — •Antje Neubauer, Jodi Szarko, Andreas Bartelt, Rainer Eichberger, Olaf Lettau, and Carlo Fasting — Hahn-Meitner-Institut, Berlin

We present fs-transient absorption measurements of perylene dyes attached to TiO2 colloidal films in ultrahigh vacuum and compare the photoinduced electron injection and recombination dynamics.

New perylene derivatives with a systematic structural change were synthesized and chemically bound to nano-structured colloidal anatase films via a carboxylic anchor group. Extending the distance between the aromatic rings of the perylene and the carboxylic anchor group starting with one double bond and going up to five double bonds also changed the photophysical properties of the dyes.

Prior to the fs-transient absorption experiments, the electronic states of the dyes in solution and bound to the TiO2 surface were studied with steady-state absorption and fluorescence spectroscopy. In all these experiments, a systematic red shift of ground, cationic, and excited state absorption bands were observed with increasing chain length.

Electron injection rates were below 30 fs, with the exception of an additional longer component in the range of 120 fs for the perylene dye with the longest chain. At the same time, the recombination process slowed down significantly with increasing chain lengths. The data suggest strong electronic coupling in the case of electron injection and weaker coupling for electron recombination.