Rate Coefficient for the Reaction N + NO

Evidence has been advanced that the rate coefficient for the reaction N + NO → N ₂ ; + O has a small positive temperature dependence at the high temperatures (900-1500 K) that prevail in the terrestrial middle and upper thermosphere by Siskind and Rusch (1992), and at the low temperatures (100-200 K) of the Martian lower thermosphere by Fox (1993). Assuming that the rate coefficient recommended by the Jet Propulsion Laboratory evaluation (DeMore et al., 1992) is accurate at 300 K, we derive here the low temperature value of the activation energy for this reaction and thus the rate coefficient that best fits the Viking 1 measured NO densities. We find that the fit is acceptable for a rate coefficient of about 1.3 × 10 ⁻¹⁰ ( T /300) ^0.5 exp(−400/T) and better for a value of about 2.5 × 10 ⁻¹⁰ ( T /300) ^0.5 exp(−600/ T ) cm ³ s ⁻¹ .