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^-7?cm³?molecule^-1?s^-1 at 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 sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.

SUBMITTER: Bones DL 

PROVIDER: S-EPMC5302016 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature