Berlin 2005 – wissenschaftliches Programm

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MO: Molekülphysik

MO 42: Poster II

MO 42.5: Poster

Dienstag, 8. März 2005, 14:00–16:00, Poster HU

Time-resolved spacer controlled electron transfer from a chromophore to a semiconductor — •Antje Neubauer, Lars Gundlach, Ralph Ernstorfer, Silke Felber, Rainer Eichberger, and Frank Willig — Hahn-Meitner-Institute, Dept. SE4, Glienicker Str. 100, 14109 Berlin, Germany

For studying the influence of rigid molecular spacer groups on the strength of the electronic coupling the organic chromophore perylene was chosen as the donor and TiO2 as the wide band gap semiconductor. It will be shown that insertion of a certain adamantane type rigid spacer group between the -COOH anchor group and the chromophore slowed down the electron transfer time from 13 fs into the range of 1 ps. The electron transfer times were measured firstly with two-photon-photoemission on the (110) surface of a rutile TiO2 single crystal and secondly with transient absorption for the same molecules anchored in the nano-structured anatase TiO2 film that is well known from the Graetzel solar cell. Whereas the former system showed one definite rate constant the latter experimental system revealed three different time constants that indicate non-ideal configurations of the chromophore with respect to the surface of the TiO2 semiconductor. Experiments will be described that address the valid time constant for the ideal adsorption configuration for the rigid spacer with respect to the surface of the semiconductor.