Kinetics and branching ratios of the reactions NH₂+NO₂->N₂O+H₂O and NH₂+NO₂->H₂NO+NO studied by pulse radiolysis combined with time-resolved infrared diode laser spectroscopy

The source reaction F + NH3 --> HF + NH2 was initiated by the pulse radiolysis of NH3/SF6 mixtures, and the primary yield of F atoms was determined by monitoring the decrease in the infrared absorption of methane consumed in the titration reaction F + CH4 --> HF + CH3. The title reactions have been studied by monitoring the decay of NH2 and the simultaneous formation of N2O and NO by time-resolved infrared diode laser spectroscopy.

The decay rate of NH2 was studied as a function of NO2 concentration to obtain an overall rate constant k(NH2 + NO2) = (1.35 +/- 0.15) X 10(-11) molecule(-1) cm(3) s(-1) at 298 K and with a bath gas pressure of p(SF6) = 40 mbar. Two product channels have been identified, N2O + H2O and H2NO + NO, with relative yields of (59 +/- 3)% and (40 +/- 5)%, respectively.