Reactions of CF₃O^- with atmospheric trace gases

The rate coefficients and product yields for the reactions of CF₃O^- with ClONO₂, HNO₃, HCl, N₂O₅, SO₂, HI, and H₂O were measured at 295 K and ~∼.4 Torr using the flowing afterglow technique. The reactions of CF₃O^- with HO₂NO₂ and H₂SO₄ were also studied qualitatively. CF₃O^- reacts rapidly with ClONO₂, HO₂NO₂, SO₂, and HCl by only fluoride transfer and with HNO₃, HI, and H₂SO₄ by both fluoride and proton transfer. CF₃O^- also reacts with HI to form IF₂^- and with N₂O₅ to produce NO₃^-. CF₃O^- undergoes a slow clustering reaction with H₂O and is transformed within water clusters into F^-·HF and F^-·(HF)₂. CF₃O^- is unreactive with CH₃NO₃, CH₃C(O)O₂NO₂, O₃, NO₂, CO₂, and O₂. These results demonstrate that CF₃O^- is an excellent candidate as a reagent ion for the selective detection of ClONO₂, HCl, and HNO₃ in the upper troposphere and stratosphere with a chemical ionization mass spectrometer. The observed reaction of CF₃O^- with H₂O within water clusters indicates that CF₃O^- will hydrolyze in aqueous solution to form F^-, HF, and CO₂. This provides insight into the mechanism for the heterogeneous loss of CF₃OH in the atmosphere.