FORMATIONS OF OH(X2-PI, A2-SIGMA+) IN THE REACTION OF NH(3-SIGMA-) WITH NO IN INCIDENT SHOCK-WAVES

Gaseous mixtures of HNCO and NO diluted in Ar were heated by incident shock waves to about 3500 K to investigate the bimolecular reaction of NH(3-SIGMA-) with NO. Ultraviolet emissions from the excited NH(A3II) and OH(A2-SIGMA+) were monitored to determine the rate constants for the ground-state reaction NH(3-SIGMA-) + NO --> N2 + OH(X2II). The branching ratio defined as the rate constant for the formation of OH relative to that for the NH(3-SIGMA-) decay was found to be 0.32 +/- 0.07 at the shock-wave temperature adopted. An intense spike of chemiluminescence due to OH(A2-SIGMA+ --> X2II) was observed, a finding which indicates a possible participation of the channel NH(3-SIGMA-) + NO --> N2 + OH(A2-SIGMA+) at high temperatures.