Remote ionization and recombination through the multichannel electron transfer

Abstract

Abstract Vibronic states of the inner mode assisting forward and backward electron transfer are taken into account in calculating position dependent rates of the process in solvents of different polarity. In polar solutions the radius of the remote reaction layer becomes shorter and the maximum rate larger if the highly exothermic electron transfer (in the inverted region) is accompanied by vibronic excitation of the products. The same is valid for the ionization of neutral reactants in non-polar solvents but not for the ion recombination that remains as distant as before although less efficient. The initial distribution of photogenerated ions with respect to the recombination zone studied previously for the one-channel reaction is reexamined. It is shown that the initial inter-ion distance increases non-monotonically with the free ionization energy as well as the charge separation quantum yield. An essential deviation of the latter from Marcus' free energy gap law is attributed to diffusion control of geminate recombination.