KINETICS OF THE REACTIONS OF NCO WITH NO AND NO2

Abstract

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 O-2. The concentration of NCO was monitored with a dye laser set at 414.95 nm. We determined k(1) = 1.73 x 10(-5) T--2.01 exp(-470/T) cm(3) 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 k(2) was observed in-this work that agrees satisfactorily with results for a shock tube(18) near 1250 K. We obtained k(2) = 6.4 x 10(-10) T--0.646 exp(164/T) cm(3) molecule(-1) s(-1) for 1250 K greater than or equal to T greater than or equal to 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. (C) 1995 John Wiley & Sons, Inc.