Statistical investigation of dissociation cross-sections for diatoms

Abstract : An efficient statistical method for investigating the mechanism and rate of simple chemical reactions was developed. The procedure involves the random selection of representative systems from the middle of the reaction zone, followed by numerical integration of the equations of motion in both directions to determine the complete course of the reaction. The approach has the important advantage over the usual one of sampling outside the reaction zone in that the fraction of systems which react is tremendously increased. The method was used to investigate the dissociation and recombination H2, O2 and I2 in collisions with Ar at temperatures of .01 and 0.1, the dissociation temperature D/k. A total of 2400 systems were followed approximately half of which resulted in a reaction. The cross-section for dissociation as a function of the internal energy H12 of the diatom was found to be proportional to 1 + (B-H12)/kt to the -3.5 power, where B is the height of the rotational barrier for the diatom. (Author)