Formation of O3+ upon ionization of O2: the role of isomeric O4+ complexes

The course of the reaction of electronically and vibronically excited metastable O(2) (+)((4)Pi(u), nu') ions with O(2), known to produce O(3) (+), was examined by the joint application of computational and mass spectrometric methods. The results show that the reaction does not proceed by a direct mechanism and that it involves instead the intermediacy of the [O(2) (+)((4)Pi(u)) x O(2)] and [O(3) (+)((4)A(2)) x O] complexes, both theoretically characterized, and the latter one positively identified by structurally diagnostic mass spectrometric techniques. The reaction is a potential source of stratospheric ozone, in that O(3) (+) ions are known to undergo efficient charge exchange with oxygen to yield neutral O(3).