Spin-orbit quenching via solvent mediated electron transfer

We simulate the 395 nm photodissociation of I2 2 embedded in clusters of 6 to 22 CO2 molecules. In the isolated molecule, photodissociation at this wavelength leads exclusively to spin-orbit excited iodine (I*) plus I. In the larger clusters we observe efficient electronic relaxation, leading both to dissociated products containing ground-state iodine and to recombined products containing I2 2 . The time scale and cluster size dependence of the spin-orbit quenching process agree well with experimental determinations of Sanov et al. ~companion paper!. The simulation trajectories show that spin-orbit quenching occurs by resonant charge transfer from solvated I to a nascent I* atom. A model derived from the theory of electron transfer reactions in solution illustrates that this resonance arises when the I spin-orbit energy is compensated by the difference between the solvation energies of the ion and the neutral. © 1999 American Institute of Physics. @S0021-9606~99!01626-8#