Abstract

Mixed-valence transition metal complexes have long been used to study electron transfer reactions due to the availability of well-defined complexes with favorable spectroscopic properties.¹ These studies have resulted in a plethora of information concerning the fundamental aspects of electron transfer reactions. We have recently used complexes of this type to investigate ultrafast electron transfer and vibrational energy relaxation dynamics in cyanide-bridged mixed-valence transition metal dimers. These studies have allowed us to observe, for the first time in the solution phase, the vibrational excitation which accompanies electron transfer reactions. In previous publications² we have shown that (1) optical excitation into the metal to metal charge transfer (MMCT) transition of a series of mixed-valence transition metal complexes leads to formation of the excited state redox isomer, and that (2) subsequent ultrafast back electron transfer regenerates the original species, with much of the electronic excitation energy being converted into vibrational energy in the product. To date we have discussed the electron transfer and the coupled vibrational excitation. Here, we concentrate on the relaxation of the vibrationally excited molecules produced following the back electron transfer.

© 1994 Optical Society of America