Kinetics of the reactions of NCO with NO and NO₂

The rate coefficients of the reactions of NCO radicals with NO and NO₂: (1) NCO + NO → products (293–836 K) and : (2) NCO + NO₂ → products (294–774 K) were measured by means of laser photolysis and laser induced fluorescence technique in the indicated temperature ranges. NCO radicals were produced from the reaction of CN, from photodissociation of ICN or BrCN, with O₂. The concentration of NCO was monitored with a dye laser set at 414.95 nm. We determined k₁ = 1.73 × 10⁻⁵ T^−2.01 exp(−470/T) cm³ molecule⁻¹ s⁻¹ that agrees with published results at room temperature and confirms the temperature dependence of an early report. A non‐Arrhenius negative temperature dependence of k₂ was observed in this work that agrees satisfactorily with results for a shock tube¹⁸ near 1250 K. We obtained k₂ = 6.4 × 10⁻¹⁰ T^−0.646 exp(164/T) cm³ molecule⁻¹ s⁻¹ for 1250 K ≥ T ≥ 294 K by combining data of these two measurements. Our result at 294 K and the temperature dependence disagree with results of two previous investigations. © 1995 John Wiley & Sons, Inc.