Ion-molecule studies of energetic oxygen allotropes in flow tubes: O 2 ( v ) , O 2 ( a Δ g 1 ) , O 3 , and O ${{\rm{O}}}_{2}({\rm{v}}),{{\rm{O}}}_{2}({\rm{a}}{}^{1}{\rm{\Delta }}_{{\rm{g}}}),{{\rm{O}}}_{3},\mathrm{and}{\rm{O}}$ .

Starting in the 1960s, flow tube apparatuses have played a central role in the study of ion-molecule kinetics, allowing for immense chemical diversity of cationic, anionic, and neutral reactants. Here, we review studies of oxygen allotropes, excluding ground state O 2 ( X 3 ∑ g - ${X}^{3}{<mpadded xmlns="http://www.w3.org/1998/Math/MathML">\sum </mpadded>}_{g}^{-}$ ), and focusing instead on reactions of cations, anions, and metal chemi-ionization reactions with ground state atomic oxygen (O 3 P), vibrationally excited molecular oxygen (O 2 (v)), electronically excited molecular oxygen (O 2 ( a 1 Δ g ${a}^{1}{{\rm{\Delta }}}_{g}$ )), and ozone (O 3 ). Historical outlines of work over several decades are given along with a focus on more recent work by our group at the Air Force Research Laboratory.