A shock tube study of H + HNCO → NH 2 + CO

The reaction of atomic hydrogen with isocyanic acid (HNCO) to produce the amidogen radical (NH 2 ) and carbon monoxide,has been studied in shock‐heated mixtures of HNCO dilute in argon. Time‐histories of the ground‐state NH 2 radical were measured behind reflected shock waves using cw, narrowlinewidth laser absorption at 597 nm, and HNCO time‐histories were measured using infrared emission from the fundamental v 2 ‐band of HNCO near 5 μm. The second‐order rate coefficient of reaction (2(a)) was determined to be:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_{2a} = 2.1 \times 10^{14}\, {\rm exp(- 8500/T,K)}} & {{\rm (f} = 0.5,{\rm F} = 1.75)} & {{\rm T = 2340} - {\rm 3270\,K,}} \\ \end{array} $$\end{document}cm 3 mol −1 s −1 , where f and F define the lower and upper uncertainty limits, respectively. An upper limit on the rate coefficient ofwas determined to be:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k_5 \le 5.0 \times 10^{11} {\rm cm}^{\rm 3}\, {\rm mol}^{{\rm - 1}} {\rm s}^{{\rm - 1}},} & {{\rm T} = 2340 - 2680\,{\rm K}{\rm .}} \\ \end{array} $$\end{document}