Photoinduced electron transfer (ET) is the fundamental process for light energy conversion. This contribution focuses on the importance of high energy vibrational modes that are excited in the course of photoinduced ET reactions. While, the influence of high energy vibrational modes on intermolecular ET between donor-acceptor pairs has been intensely investigated, ET induced excitation of vibrational modes in heterogeneous donor-acceptor systems is a phenomenon that hitherto has been given little attention. By comparing the electron transfer spectrum of photoinduced ET at room temperature and at liquid Helium temperature we found that a large amount of energy (~340 meV) is transferred from the electronic excited donor state of perylene dye molecules to vibrational excitation of the resulting cation molecular product during ET to TiO2acceptor states. The experimental data has allowed for the first detailed comparison with different theories that have been suggested for modeling ultrafast photoinduced ET reactions. This talk is a tribute to the pioneering work on photo-electrochemical processes at surfaces by our late friend and colleague Professor Frank Willig.Fig. 1) Scheme illustrating the origin of the energy distribution after photoinduced ultrafast non-adiabatic heterogeneous electron transfer from a molecular donor to a semiconductor.

Spectra for ultrafast photoinduced heterogeneous electron transfer reveal importance of high energy vibrational modes

246th National Meeting (2013)

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