Ultrafast experiments on intermolecular electron transfer in the benzene - bromine atom charge transfer complex

Abstract

Ultrafast pump - probe measurements have been made on the benzene - bromine atom charge transfer (CT) complex in CCl 4 and cyclohexane solutions. Ultrafast optical excitation of the CT band of the complex yields an ion pair, which is comprised of a benzene cation and a bromide anion. The rate of charge recombination between the bromide and the benzene cation in the ion pair has been observed to be much faster than the rate of diffusion apart. The charge recombination rate is accelerated at high benzene concentrations as a result of the formation of a benzene dimer cation - bromide ion pair which undergoes much faster charge recombination than the benzene cation - bromide ion pair.