title: Weak acids enhance halogen activation on atmospheric water's surfaces.
abstract: We report that rates of I(2)(g) emissions, measured via cavity ring-down spectroscopy, during the heterogeneous ozonation of interfacial iodide: I(-)(surface, s) + O(3)(g) + H(+)(s) →→ I(2)(g), are enhanced several-fold, whereas those of IO·(g) are unaffected, by the presence of undissociated alkanoic acids on water. The amphiphilic weak carboxylic acids appear to promote I(2)(g) emissions by supplying the requisite interfacial protons H(+)(s) more efficiently than water itself, at pH values representative of submicrometer marine aerosol particles. We infer that the organic acids coating aerosol particles ejected from ocean's topmost films should enhance I(2)(g) production in marine boundary layers.
authors.affiliation: Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Hayase
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yabushita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Shinichi
authors.initials: S
authors.lastname: Enami
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hoffmann
authors.forename: Agustín J
authors.initials: AJ
authors.lastname: Colussi
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007455:Iodine / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D014867:Water; D007455:Iodine