Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 4: Femtosecond Spectroscopy I

MO 4.6: Talk

Monday, March 14, 2011, 15:45–16:00, TOE 317

Electron Injection from Perylene Derivates to ZnO Nanorods Studied by Time Resolved Optical and Terahertz Absorption Spectroscopy — •Christian Strothkaemper, Robert Schütz, Andreas Bartelt, Thomas Hannappel, and Rainer Eichberger — Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14019 Berlin, Germany

We investigated the photo-induced heterogeneous electron transfer from perylene derivatives to ZnO nanorods by transient absorption (TA) and optical pump terahertz probe (OPTP) spectroscopy. The perylene derivatives where systematically varied by changing the length of the molecular bridge group. While TA spectroscopy allows for a selective probing of the different states of the dye OPTP is sensitive only to the injected electrons in the ZnO. The recombination of the injected electron with the cationic dye was found to slow down with increasing bridge length. This can be explained by a reduced electron-cation interaction for longer bridges. On the other hand the injection velocity as measured by OPTP shows no clear trend concerning the bridge length. Furthermore we observed a discrepancy between the buildup of the cationic signal (TA) and that of free electrons (OPTP). Reasons for the observed difference are discussed and compared to existing models.