Transition states of charge‐transfer reactions: Femtosecond dynamics and the concept of harpooning in the bimolecular reaction of benzene with iodine

We describe an approach for real‐time studies of the transition‐state dynamics of charge‐transfer reactions. An application to the bimolecular reaction of benzene with iodine is reported. The measured 750±50 fs transient growth of the free I atom product elucidates the nature of the transition state and the mechanism for the dissociative charge‐transfer reaction. The mechanism is formulated in relation to the impact geometry and the dative bonding, which are crucial to condense‐phase and surface reactions, and is supported by molecular dynamics.