Production of NO⁺(a ³Σ⁺) ions in the reaction of N⁺ ions with O₂ at 300 K

It is well known that NO⁺ ions constitute about 45% of the product ions of the ionospherically important reaction of N⁺ ions with O₂. However, NO⁺ ions in both the ground X ¹Σ⁺ state and the metastable a ³Σ ⁺ state are energetically possible. The present study uses a selected-ion flow tube to determine the percentage of NO⁺(a ³Σ⁺) product ions. It is known from separate studies that NO⁺(a ³Σ⁺) ions react rapidly with N₂ to form N₂⁺; therefore, the addition of N₂ and the occurrence of N₂⁺ ions provide a monitor for the possible NO⁺(a ³Σ⁺) product ions from the N⁺ reaction with O₂. It is found that NO⁺(a ³Σ⁺) production accounts for less than 2% of the total rate constant at 300 K.