Kinetics of reactions of ground state nitrogen atoms 4S32 with NO and NO2

The discharge flow technique has been used with resonance fluorescence detection of N atoms to study the fast radical-radical re ction ofground state nitrogen atoms (4S3/2) with NO and NO 2. The rate constants obtained are (in units of cm 3 molecule -• s -j) k• = (2.2 + 0.2) x 10-•1exp[(160 + 5 )/T] in the temperature range 213 K _< T _< 369 K for N + NO --> N 2 qO and k 2 = (5.8 + 0.5) x 10 -12 exp [(220 + 50)/T] in the temperature range 223 K < T _< 366 K for N qNO2 --> N20 qO. 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 R1 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 i the calculated concentrations of NOy.