P121
Ultrafast electron transfer in tetracyanoethylene complexes with benzene and toluene.
Wlodzimierz Jarzeba, Shigeo Murata*, M. Tachiya*
Jagiellonian University, (*)NIMC

The ultrafast spectroscopy of the electron donor-acceptor complexes of tetracyanoethylene with benzene and toluene has been investigated in polar and nonpolar solvents. After ultrafast excitation of the charge transfer band, formation of the contact ion pair is observed. The decay time of the contact ion pair is observed on a time scale from 1 ps to 1 ns depending on the solvent. In this study we present dependence of the back electron transfer rate on the driving force for the TCNE-benzene and TCNE-toluene systems in different solvents. The absolute rate constants for the nonradiative return electron transfer in nonpolar solvents can be predicted using a coventional nonadiabatic theory of electron transfer and information from the analysis of the fluorescence spectra of the complexes. The rate constants in polar solvents are obtained applying the empirical polarity scale based on the dynamic Stokes shift of coumarin 153.
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