Mechanism of chemiluminescent reaction between nitric oxide and ozone

Abstract

The absolute intensity and quenching constants of the NO₂ emission in the chemiluminescent reaction between nitric oxide and ozone have been determined using a large capacity-flow reactor at low pressures. These studies have confirmed the mechanism previously proposed: NO+O₃= NO^*₂(²B₁)+O₂(1a) NO+O₃= NO₂(²A₁)+O₂(1b) NO^*₂= NO₂+hv(2) M+NO₂= NO₂+M (3) The rate constants of the primary steps are k_1a=(7.6 ± 1.5)× 10¹¹ exp (–4180 ± 300/RT) and k_1b=(4.3 ± 1.0)× 10¹¹ exp (–2330 ± 150/RT) cm³ mole^–1 sec^–1. The half-quenching pressures (k₂/k_3m) of electronically excited NO₂ produced are: Ar = 13.0 ± 1.0 µ, O₂= 8.3 ± 0.5 µ, NO = 5.2 ± 0.3 µ, NO₂= 3.7 ± 0.1 µ. The detailed mechanism of reactions (1a) and (1b) is discussed.