The reaction of hydrated iodide I(H2O)− with ozone: a new route to IO2− products

Abstract

We report on an experimental characterization of the isolated reaction of hydrated iodide I(H₂O)⁻ with ozone O₃ at room temperature performed using a radio-frequency ion trap combined with a quadrupole mass spectrometer. Contrary to the oxidation reaction of the bare I⁻ ion, the hydrated iodide I(H₂O)⁻ primarily reacts to form I⁻ and IO₂⁻ with significant absolute reaction rate constants of 2.0 ± 0.3 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ and 2.5 ± 0.3 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ while direct pathways to IO⁻ and IO₃⁻ are much weaker. Quantum chemical calculations indicate that in aqueous phase and for atmospherically relevant temperatures, the presence of hydrated iodides are favored over bare I⁻ ions, thus suggesting that the chemistry of the hydrated ions is relevant for understanding and modeling atmospheric processes at the air–water interface.