Kinetic study of reaction C2H5+ HO2in a photolysis reactor with time-resolved Faraday rotation spectroscopy

Hongtao Zhong, Chao Yan, Chu C. Teng, Guoming Ma, Gerard Wysocki, Yiguang Ju

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3 Scopus citations


The rate constant and branching ratios of ethyl reaction with hydroperoxyl radical, C2H5 + HO2 (1), a key radical-radical reaction for intermediate temperature combustion chemistry, were measured in situ for the first time in a photolysis Herriott cell by using mid-IR Faraday rotation spectroscopy (FRS) and UV-IR direct absorption spectroscopy (DAS). The microsecond time-resolved diagnostic technique enabled the direct rate measurements of the target reaction at 40 and 80 mbar and reduced the experimental uncertainty considerably. C2H5 and HO2 radicals were generated by the photolysis of (COCl)2/C2H5I/CH3OH/O2/He mixture at 266 nm. By direct measurements of the transient profiles of C2H5, HO2 and OH concentrations, the overall rate constant for this reaction at 297 K was determined as k 1 (40 mbar) = (3.8 ± 0.8) × 10−11 cu cm/molecule−s and k1 (80 mbar) = (4.1 ± 1.0) × 10−11 cu cm/molecule−s . The direct observation of hydroxyl radical (OH) indicated that OH formation channel was the major channel with a branching ratio of 0.8 ± 0.1.

Original languageEnglish (US)
Pages (from-to)871-880
Number of pages10
JournalProceedings of the Combustion Institute
Issue number1
StatePublished - 2021
Event38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: Jan 24 2021Jan 29 2021

All Science Journal Classification (ASJC) codes

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


  • Chemical kinetics
  • Faraday rotation spectroscopy
  • Hydroperoxyl radical
  • Radical-radical reaction
  • Rate constant


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