Kinetics of N3+ and N4+ with N(4S), O(3P), and NO

Abstract

Kinetics of the reactions of N₃⁺ and N₄⁺ with N(⁴S) and O(³P) are measured at room temperature using a flowing afterglow-selected ion flow tube apparatus. Oxygen atoms are produced by titrating NO against nitrogen atoms formed from a microwave discharge of N₂. The reaction rate constants are generally well-described by assuming strict spin-conservation along with Langevin capture kinetics. N₃⁺ + N occurs with k = 1.8 × 10⁻¹⁰ cm³ s⁻¹, spin state counting indicates both doublet and quartet states of N₂⁺ are formed. N₄⁺ + N occurs with k = 2.2 × 10⁻¹⁰ cm³ s⁻¹, yielding exclusively N₃⁺. The N₃⁺ + O reaction occurs with k = 2.5 × 10⁻¹⁰ cm³ s⁻¹, yielding significant amounts of NO⁺ and N₂⁺ products. N₄⁺ + O, the only of these reactions without any spin-constraint, is the only reaction to occur near the Langevin capture rate with k = 5.6 × 10⁻¹⁰ cm³ s⁻¹. The major product of the N₄⁺ + O reaction is charge transfer to yield O⁺ (k = 4.1 × 10⁻¹⁰ cm³ s⁻¹) with N₂O⁺ (k = 7.7 × 10⁻¹¹ cm³s⁻¹) and probably NO ⁺ formed as minor products. The reaction of N₄⁺ + NO minimally occurs with k < 6.5 × 10⁻¹² cm³ s⁻¹. A novel method of assessing uncertainties in rate constants derived from complicated chemical reaction networks is presented, yielding probability density curves as a function of each partial rate constant. The analysis obviates the need of assuming experimental errors of the rate constants are normally distributed.