REACTIONS OF O₂ ⁺ :O₂ WITH CO₂, O₃, AND O₂ plus :O₃ WITH H₂O AND CH₄ AND THEIR ROLE IN STRATOSPHERIC ION CHEMISTRY.

Thr reactions of O//2** plus :O//2 ions with the minor stratospheric neutrals CO//2, O//3, and CH//4 have been studied in a variable temperature flowing afterglow to test whether they represent reaction paths that can compete with the one leading to H//3O** plus :nH//2O ions and hence can offer the possibility of different terminal ions. The reaction of O//2** plus :O//2 with CH//4 was found to be too slow to be competitive. The measured equilibrium constants of the reactions with CO//2 and O//3 indicated that only the latter, which had an O//2** plus :O//3 product, could play a stratospheric role. The O//2** plus :O//3 ion chemistry was also examined. It was found that the reaction with CH//4 was immeasurably slow but that the reaction with H//2O was fast, yielding O//2** plus :H//2O ions. Since this product ion is part of the sequence of reactions that lead to the H//3O** plus :nH//2O ions, it is concluded that CO//2, O//3, and CH//4 do not afford alternative reaction paths that could rationalize the recent in situ observation of non-H// 3O** plus :nH//2O ions in the lower stratosphere.