Near-IR kinetic spectroscopy (IRKS) of the HO2 and C2H5O2 self and cross reactions

Aaron C. Noell, Leah S. Alconcel, D. J. Robichaud, Mitchio Okumura, S. P. Sander

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Peroxy radical (RO2) chemistry is central to the oxidation of volatile organic carbon in the troposphere. Kinetic studies of their reactions are rendered difficult by competing self- and cross-reactions, especially the poorly characterized secondary production of HO2 from RO2 self-reactions. In this experiment C2H5O2 and HO2, were generated by pulsed laser photolysis and monitored simultaneously and independently using UV absorption and wavelength modulation near-IR spectroscopies. Their self- and cross-reactions were investigated over a wide range of relative concentrations, at T=221-296 K and p=50-200 Torr. The Arrhenius expression for the cross reaction rate constant is k2(T) = (5.58±1.80) × 10-13 exp(672±74) cm3 molecules-1 s-1, and is in general agreement with previous studies. The high sensitivity for HO2 detection led to the first direct measurement of the branching fraction to the radical channel in the C2H5O2 self-reaction. The result, α = 0.24±0.05 is less than half that reported in the literature.

Original languageEnglish
Title of host publicationAmerican Chemical Society - 235th National Meeting, Abstracts of Scientific Papers
Publication statusPublished - 2008
Event235th National Meeting of the American Chemical Society, ACS 2008 - New Orleans, LA, United States
Duration: 6 Apr 200810 Apr 2008

Publication series

NameACS National Meeting Book of Abstracts
ISSN (Print)0065-7727


Conference235th National Meeting of the American Chemical Society, ACS 2008
Country/TerritoryUnited States
CityNew Orleans, LA

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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