A set of model cross sections for the Monte Carlo simulation of rarefied real gases: Atom–diatom collisions

A set of model cross sections for atom–diatom collisions is presented for use in the Monte Carlo simulation of rarefied real gases and in the master relaxation equation. The elastic and rotationally inelastic cross sections are taken as the variable-soft-sphere and statistical-inelastic-cross-section models, respectively. The vibrationally inelastic and dissociation cross sections are derived by combining the improvement-to-forced-oscillator-impulsive-transfer-semiclassical vibrational transition probability and the weak-vibrational-bias dissociation probability, respectively, with the line-of-centers cross section. The recombination is modeled by the two-step binary collision process with two cross sections for the formation and stabilization of an orbiting pair. Assessment of reality and feasibility of the model cross sections is made by comparing the master-relaxation-equation and Monte Carlo results with available experimental data of the vibrational relaxation time, dissociation rate constant and induction time, and recombination rate constant of oxygen diluted in argon.