A shock-tube study of the N2O + M ⇆ N2 + O + M (M = Ar) rate constant using N2O laser absorption near 4.6 μm

The low-pressure limit rate constant k(1,0) of the reaction N2O + M reversible arrow N-2 + O + M was measured in shock-heated mixtures of 0.2% N2O/Ar using 4.56-mu m laser absorption of N2O in the temperature range 1546-2476 K near 1.3 atm. Modeling the N2O profiles with a detailed kinetic analysis, which considered non-ideal pressure variations, provided k(1,0) values that were best fit by the expression k(1,0) =1.01 x 10 15 exp(-30, 050/T), with k 1 , 0 in cm(3) mol(-1) s(-1) and T in K. Estimated k(1,0) uncertainties at 1546, 1821, and 2230 K were respectively 13.0%, 8.9%, and 9.0%. By combining the results of the present study with previous low-temperature data measured in flow/static reactors, the best fit over the temperature range 850-2500 K was determined to be (k(1,0) in cm(3) mol(-1) s(-1) , T in K) k(1,0) = (1.04 I 0.04 x 10(15))exp[ (30, 098 +/- 90)/T]. This is the first study of k(1,0) using N2O infrared laser absorption. Through the high signal-to-noise ratios of the experimental N2O profiles and careful consideration of dP/dt effects, this k(1,0) determination is in excellent agreement with the large body of historical k(1,0) data but demonstrates significantly less scatter than all previous measurements. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

This study measured the low-pressure limit rate constant of the N2O + M reaction using laser absorption spectroscopy and analyzed the results with excellent agreement with historical data. The determined expression for the rate constant showed better stability and precision over a wide temperature range.