KINETICS OF REACTIONS OF GROUND-STATE NITROGEN-ATOMS (S-4(3/2)) WITH NO AND NO2

The discharge flow technique has been used with resonance fluorescence detection of N atoms to study the fast radical-radical reaction of ground state nitrogen atoms (S-4(3/2)) with NO and NO2. The rate constants obtained are (in units of cm(3) molecule(-1) s(-1)) k(1) = (2.2 +/- 0.2) x 10(-11) exp[(160 +/- 50)/T] in the temperature range 213 K less than or equal to T less than or equal to 369 K for N + NO --> N-2 + O and k(2) = (5.8 +/- 0.5) x 10(-12) exp [(220 +/- 50)/T] in the temperature range 223 K less than or equal to T less than or equal to 366 K for N + NO2 --> N2O + O. The reported error limits are at the 95% confidence level. The reaction kinetics are consistent with other radical-radical reactions, essentially no enthalpic barrier is observed. Substitution of the measured rate of R, for the value recommended in the latest Jet Propulsion Laboratory compendium [DeMore et al., 1992] results in a small change in the concentration of ozone predicted in a two-dimensional photochemical model. Modeled ozone concentrations are higher (approximately 1%) in the high-latitude upper stratosphere as a result of a 3-10% reduction in the calculated concentrations of NOy.