title: A study of the dissociative recombination of CaO+with electrons: Implications for Ca chemistry in the upper atmosphere.
abstract: The dissociative recombination of CaO+ions with electrons has been studied in a flowing afterglow reactor. CaO+was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar+ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10-7cm3molecule-1s-1at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca+/Fe+ratio is ~8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca+ions in a descending sporadicElayer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.
authors.affiliation: School of Chemistry University of Leeds Leeds UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Bones
authors.affiliation: Leibniz Institute of Atmospheric Physics Rostock University Kühlungsborn Germany.
authors.forename: M
authors.identifier: 0000-0002-5382-4017
authors.initials: M
authors.lastname: Gerding
authors.affiliation: Leibniz Institute of Atmospheric Physics Rostock University Kühlungsborn Germany.
authors.forename: J
authors.initials: J
authors.lastname: Höffner
authors.affiliation: School of Chemistry University of Leeds Leeds UK.
authors.forename: Juan Carlos Gómez
authors.identifier: 0000-0001-7972-085X
authors.initials: JC
authors.lastname: Martín
authors.affiliation: School of Chemistry University of Leeds Leeds UK.
authors.forename: J M C
authors.identifier: 0000-0003-3648-6893
authors.initials: JM
authors.lastname: Plane
keywords: dissociative electron recombination; ion‐molecule chemistry; meteoric metal layers; sporadic layers