Rates of formation of ozone isotopomers: a theoretical interpretation

It is found that the relative probabilities for the 0→1 vibrational excitation in collisions of oxygen isotope aO atom approaching bOcO molecule along a path which has essentially the same geometry as the ozone dissociation path in the asymptotic region coincide quite well with the observed relative formation rates of the aObOcO isotopomers formed in aO+bOcO collisions. It may thus be concluded that isotope selectivity in ozone formation arises primarily from the transfer of the excess kinetic energy of the relative motion into the O2 vibration which produces a vibrationally excited O3* and not from the subsequent collisional deactivation and stabilization through the bath gas. This is in accord with the conclusions arrived at in the recent experimental studies of third-body dependence of ozone formation rates. Further arguments about third-body effects are presented in support of the model.