Mass spectrometry of interfacial layers during fast aqueous aerosol/ozone gas reactions of atmospheric interest

Abstract

The oxidations of sulfite and iodide in the interfacial layers of aqueous microdroplets exposed to O_3(g) for 1 ms are investigated by online mass spectrometry of the electrostatically ejected anions. S(IV) oxidation losses in Na_2SO_3 microdroplets are proportional to [S(IV)] [O_3(g)] up to ∼90% conversion. I^− is more abundant than HSO_3^- in the interfacial layers of equimolar (Na_2SO_3 + NaI) microdroplets and ∼3 times more reactive than image toward O_3(aq) in bulk solution, but it is converted with minimal loss to I_3^- and IO_3^- plus a persistent ISO_3^- intermediate. These observations reveal unanticipated interfacial gradients, reactivity patterns and transport phenomena that had not been taken into account in previous treatments of fast gas–liquid reactions.

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