Vibrational control of molecular electron transfer reactions

ABSTRACT

Vibrational motions promote molecular electron transfer (ET) reactions by bringing electron donor and electron acceptor electronic states to fleeting resonance, and by modulating the donor-to-acceptor electronic coupling. The main experimental signature of molecular motion effects on the ET rate is the temperature dependence of the rate, which gives information about the overall free energy activation barrier for the ET reaction. Another approach to probing the vibrational control of ET reactions is to excite specific electron-transfer-active vibrational motions by external infrared (IR) fields. This type of experimental probe is potentially more specific than thermal excitation and recent experiments have shown that molecular ET rates can be perturbed by mode-specific IR driving. We review the theory and experiments of vibrational control of ET rates, and discuss future challenges that need to be tackled in order to achieve the mode-specific tuning of rates.