Resonance Raman Spectrum Does Not Predict Vibrational State Distributions Caused by Ultrafast Reverse Electron Transfer of (CN)5FeCNRu(NH3)5

Abstract : It is generally thought that the resonance Raman spectrum can he used to predict the vibronic paths of radiationless decay or intramolecular electron transfer (ET) following electronic photoexcitation. We show that this assumption does not hold for the S (sub 1) --> S(sub 0) ET of (CN)5 Fe-III CN Ru-II (NH3)5(-) in solution following S(sub 0) ---> S(sub 1) optical excitation. Instead, vibrational modes that are not observed in the charge transfer resonance Raman spectrum, i.e., are not immediately displaced with photoexcitation of the ground electronic state, are active in the reverse, radiationless ET process.