Kinetics of CO and H atom production from the decomposition of HNCO in shock waves

The production of CO and H atoms from the thermal decomposition of HNCO in shock waves at temperatures between 2120 and 2570 K has been measured by resonance absorption. Kinetic modeling of these product formation rates using a recently established mechanism yielded the second-order rate constants for the primary decomposition processes HNCO + Ar → NH + CO + Ar (1) and HNCO + Ar → H + NCO + Ar (2): k₁ = 10^15.41±0.16 exp(-39800 ± 700/T) cm³/(mol·s) and k₂ = 10^17.0 exp(-56400/T) cm³/(mol·s). The values of k₁ determined in this work agree quantitatively with those reported recently by Hanson, Bowman, and co-workers. Combination of these two sets of data gives rise to the Arrhenius expression k₁ = 10^{15.925±0.085} exp(-42640 ± 450/T) cm³/(mol·s) for 1830 K ≤ T ≤ 3340 K.