Resonance absorption measurements of N and O atoms in high temperature no dissociation and formation kinetics

Abstract

The dissociation of NO has been measured in the temperature range 2400 K≤T≤6200 K using a shock tube technique. The test gas mixtures, consisting of Ar with relative NO concentrations between 10 and 10 000 ppm, were heated by reflected shock waves, and the concentrations of N and O atoms in the post-shock region were monitored using atomic resonance absorption spectroscopy (ARAS). Rate coefficients of the reactions N O + A r → 1 N + O + A r N O + N O → 3 N 2 O + O k1=1.6·10−9 exp(−74 700 K/T) cm3s−1 (±40%) k3=1.5·10−11 exp (−35 000 K/T) cm3s−1 (±40%) could be determined directly from the measured atom concentrations. Additionally, the rate coefficient of the NO formation reaction. O + N 2 → 9 N O + N k9=3.0·10−10 exp(−38 300 K/T) cm3s−1 (±40%) was determined by O and N atom concentration measurements in shock heated N2/N2O/Ar mixtures. The experiments were conducted in the temperature range 2400 K≤T≤4100 K at pressures of about 1.4 bar. Complete agreement with the results of Monat, Hanson and Kruger7 was obtained.