A shock tube study of reactions of atomic oxygen with isocyanic acid

Reactions of atomic oxygen with isocyanic acid (HNCO) have been studied in incident and reflected shock wave experiments using HNCO/N₂O/Ar mixtures. Quantitative time-histories of the NH(X³Σ^?) and OH(X²Π_i) radicals were measured behind the shock waves using cw, narrow-linewidth laser absorption at 336 nm and 307 nm, respectively. The second-order rate coefficients of the reactions: and were determined from early-time NH and OH formation rates, with least-squares two-parameter fits of the results given by: and cm³ mol^?1 s^?1. The minimum and maximum rate constant factors (?,F) define the lower and upper uncertainty limits, respectively. An upper limit on the rate coefficient of was determined to be: .