Master equation simulation of O_2-N_2 collisions on an ab-initio potential energy surface

摘要

Simulation of vibrational energy transfer in O_2-N_2 collisions is conducted using the quasiclassical trajectory method on an accurate potential energy surface. State-resolved rate coefficients are obtained for the O_2 and N_2 vibrational ladders at temperatures between 8000 and 15,000 K. A system of master equations is constructed using the new dataset in order to simulate nonequilibrium conditions observed in shock flows. The relaxation time derived from a solution of the master equations is in good agreement with the Millikan and White correlation at lower temperatures with an increasing discrepancy toward the translational temperature of 15,000 K. At the same time, the master equation relaxation time is similar to that derived under the assumption of a two-state system. This observation suggests that the multiquantum vibrational energy transfer in O_2-N_2 may be less efficient compared to that in a chemically reactive molecule-atom system.