Although photoinduced electron transfer (ET) reactions have been investigated
both experimentally and theoretically for several decades, there are still several unanswered questions.
Those we are currently trying to answer are the following:
1 » The absence of inverted region in bimolecular photoinduced ET reaction.
The inverted region predicted by Marcus theory has been observed for intramolecular charge separation,
charge shift and charge recombination processes, for charge recombination of geminate ion pair, but never for intermolecular ET quenching.
2 » The free energy dependence of the charge recombination (CR) in excited donor/acceptor complexes (DACs) or in contact ion pairs (CIPs) departs considerably from theoretical predictions. First, the logarithm of the CR rate constant kCR exhibits a linear free energy dependence, i.e. kCR increased with decreasing driving force. Second this dependence has been observed down to very low driving forces and therefore the normal region, predicted by Marcus theory, is not observed. (more)
3 » The structure of the various intermediates involved in bimolecular photoinduced ET processes is not known. For example, contact ion pairs (CIP), loose ion pairs (LIP), and free ions have essentially the same absorption spectrum and the only evidence of the existence of some of these species comes from kinetics. (more)
Contact:
Eric Vauthey
Physical Chemistry Department - Sciences II - University of Geneva
30, Quai Ernest Ansermet - CH-1211 Geneva 4 (Switzerland)
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