Kinetics of associative detachment of O- + N2 and dissociative attachment of e- + N2O up to 1300 K: chemistry relevant to modeling of transient luminous events

The rate constants of O- + N<INF>2</INF> -> N<INF>2</INF>O + e- from 800 K to 1200 K and the reverse process e- + N<INF>2</INF>O -> O- + N<INF>2</INF> from 700 K to 1300 K are measured using a flowing afterglow - Langmuir probe apparatus. The rate constants for O- + N<INF>2</INF> are well described by 3 x 10-12 e-0.28 eV kT<SUP>-1</SUP> cm3 s-1. The rate constants for e- + N<INF>2</INF>O are somewhat larger than previously reported and are well described by 7 x 10-7 e-0.48 eV kT<SUP>-1</SUP> cm3 s-1. The resulting equilibrium constants differ from those calculated using the fundamental thermodynamics by factors of 2-3, likely due to significantly non-thermal product distributions in one or both reactions. The potential surfaces of N<INF>2</INF>O and N<INF>2</INF>O- are calculated at the CCSD(T) level. The minimum energy crossing point is identified 0.53 eV above the N<INF>2</INF>O minimum, similar to the activation energy for the electron attachment to N<INF>2</INF>O. A barrier between N<INF>2</INF>O- and O- + N<INF>2</INF> is also identified with a transition state at a similar energy of 0.52 eV. The activation energy of O- + N<INF>2</INF> is similar to one vibrational quantum of N<INF>2</INF>. The calculated potential surface supports the notion that vibrational excitation will enhance reaction above the same energy in translation, and vibrational-state specific rate constants are derived from the data. The O- + N<INF>2</INF> rate constants are much smaller than literature values measured in a drift tube apparatus, supporting the contention that those values were overestimated due to the presence of vibrationally excited N<INF>2</INF>. The result impacts the modeling of transient luminous events in the mesosphere.