Direct kinetic measurements of criegee intermediate (CH 2OO) formed by reaction of CH 2I with O 2

Oliver Welz, John D. Savee, David L. Osborn, Subith S. Vasu, Carl J. Percival, Dudley E. Shallcross, Craig A. Taatjes

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Ozonolysis is a major tropospheric removal mechanism for unsaturated hydrocarbons and proceeds via "Criegee intermediates"-carbonyl oxides-that play a key role in tropospheric oxidation models. However, until recently no gas-phase Criegee intermediate had been observed, and indirect determinations of their reaction kinetics gave derived rate coefficients spanning orders of magnitude. Here, we report direct photoionization mass spectrometric detection of formaldehyde oxide (CH 2OO) as a product of the reaction of CH 2I with O 2. This reaction enabled direct laboratory determinations of CH 2OO kinetics. Upper limits were extracted for reaction rate coefficients with NO and H 2O. The CH 2OO reactions with SO 2 and NO 2 proved unexpectedly rapid and imply a substantially greater role of carbonyl oxides in models of tropospheric sulfate and nitrate chemistry than previously assumed.
    Original languageEnglish
    Pages (from-to)204-207
    Number of pages3
    JournalScience
    Volume335
    Issue number6065
    DOIs
    Publication statusPublished - 13 Jan 2012

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