A SHOCK-TUBE STUDY OF H + HNCO -] NH2 + CO

The reaction of atomic hydrogen with isocyanic acid (HNCO) to produce the amidogen radical (NH2) and carbon monoxide, [GRAPHICS] has been studied in shock-heated mixtures of HNCO dilute in argon. Time-histories of the ground-state NH2 radical were measured behind reflected shock waves using cw, narrow-linewidth laser absorption at 597 nm, and HNCO time-histories were measured using infrared emission from the fundamental upsilon-2-band of HNCO near 5-mu-m. The second-order rate coefficient of reaction (2(a)) was determined to be: k2a = 2.1 x 10(14) exp(-8500/T,K) (f = 0.5,F = 1.75) T = 2340-3270 K, cm3 mol-1 s-1, where f and F define the lower and upper uncertainty limits, respectively. An upper limit on the rate coefficient of [GRAPHICS] was determined to be: k5 less-than-or-equal-to 5.0 x 10(11) cm3 mol-1 s-1, T = 2340-2680 K.