Electron attachment and negative ion-molecule reactions in nitrous oxide

Abstract

The negative ions formed in N₂O and N₂O and N₂O + O₂ mixtures have been studied in the gas phase using a drift tube and mass filter. Gas pressures were in the Torr range, and reduced fields were varied between 10^–17 and 10^–15 V cm² molecule^–1. The observed ion spectrum was found to be governed by the following reaction, with their associated thermal rate constants: e + N₂O → N₂+ O^–, k₁= 4 × 10^–15 cm³ molecule^–1 s^–1, O^–+ N₂O → NO^–+ NO, k₃=(1.95 ± 0.06)× 10^–10 cm³ molecule^–1 s^–1, NO^–+ N₂O → NO^–₂+ N₂, k₄=(2.8 ± 0.2)× 10^–14 cm³ molecule^–1 s^–1, NO^–+ 2N₂O → N₃O^–₂+ N₂O, k₅=(8.5 ± 1.5)× 10^–30 cm⁶ molecule^–2 s^–1, O^–+ 2N₂O → N₂O^–₂+ N₂O, k₆=(4.2 ± 0.5)× 10^–29 cm⁶ molecule^–2 s^–1, NO^–+ N₂O → N₂O + NO + e, k₁₁=(6.0 ± 1.0)× 10^–12 cm³ molecule^–1 s^–1, O^–₂+ N₂O → O^–₃+ N₂, k₁₀ < 10^–12 cm³ molecule^–1 s^–1. The rates of reaction, (5), (6) and (11) were weak functions of reduced field. In no experiment was any evidence found for the existence of a long-lived N₂O^– ion.