Application of RRKM theory to the reactions OH + NO₂+ N₂→ HONO₂+ N₂(1) and ClO + NO₂+ N₂→ ClONO₂+ N₂(2); a modified gorin model transition state

Rate constants as a function of both temperature and pressure were calculated for the title reactions using RRKM theory in conjunction with a modified Gorin transition state. The modification introduces a hindrance parameter which accounts for repulsive interactions between the rotating fragments. At the highest stratospheric pressures (∼50 torr) and at stratospheric temperature (∼220°K), the extent of “falloff” from first‐order [N 2 ] dependence is ∼70% for reaction (1) and ∼35% for reaction (2).