Impact of Criegee Intermediate Reactions with Peroxy Radicals on Tropospheric Organic Aerosol

Rabi Chhantyal Pun*, M. Anwar H. Khan, Nicholas Zachhuber, Carl Percival, Dudley E Shallcross, Andrew J Orr-Ewing

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

17 Citations (Scopus)
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Peroxy radicals and carbonyl oxides (Criegee intermediates) are produced in the troposphere during OH and ozone-initiated oxidation of hydrocarbons. Reactions between these species have previously been shown to form highly oxidized molecules which can condense to form secondary organic aerosols. Here, cavity ring-down spectroscopy coupled with laser flash photolysis was used to measure directly rate coefficients for reactions of CH2OO with CH3O2 and CH3C(O)O2. The rate coefficients were found to be similar within the measurement uncertainties and only weakly dependent on temperature (in the range 243 – 310 K) and pressure (10 - 100 Torr, N2). A combined rate coefficient of k (CH2OO+RO2, RO2 = CH3O2/CH3C(O)O2) = (2.4 ± 1.2) × 10-11 cm3 molecule-1 s-1 was obtained under these conditions. Global modelling using STOCHEM-CRI, updated with monoterpene chemistry generating Criegee intermediates, and supplemented by regional box modelling, shows that this class of Criegee intermediate + peroxy radical reactions can contribute up to ~1.3% of secondary organic aerosol production in forested regions of the world.
Original languageEnglish
Article number10
Pages (from-to)1743-1755
Number of pages13
JournalACS Earth and Space Chemistry
Early online date26 Aug 2020
Publication statusPublished - 15 Oct 2020


  • atmospheric chemistry
  • Criegee intermediates
  • peroxy radicals
  • radical reactions
  • secondary organic aerosol
  • cavity ring-down spectroscopy chemical transport modeling


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