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Yield of Formyl Radical from the Vinyl + O 2 Reaction
Author(s) -
Matsugi Akira,
Miyoshi Akira
Publication year - 2014
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20823
Subject(s) - chemistry , radical , reaction rate constant , dissociation (chemistry) , yield (engineering) , photodissociation , torr , photochemistry , kinetics , organic chemistry , thermodynamics , physics , quantum mechanics
The yield of formyl (HCO) radical from the reaction of vinyl (C 2 H 3 ) radical with O 2 has been investigated by using a pulsed laser photolysis/cavity ring‐down spectroscopy technique at room temperature. The rate constants for the C 2 H 3 + O 2 and HCO + O 2 reactions were measured to be (8.60 ± 0.87) × 10 −12 and (5.55 ± 1.00) × 10 −12 cm 3 molecule −1 s −1 , respectively, which were consistent with preceding studies. The yield of HCO radical was determined to be ϕ (HCO) = 0.222 ± 0.066, and it was independent of pressure in the pressure range 10–100 Torr with He or N 2 buffer. The Rice–Ramsperger–Kassel–Marcus calculation combined with a prior energy distribution model could reproduce the experimental HCO‐radical yield and indicated that a significant portion of HCO radicals formed in the C 2 H 3 + O 2 reaction promptly dissociated to H + CO. The first CO‐stretch excited state of HCO radical, HCO(0,0,1), was observed at the total pressure of 1 Torr; the time profiles of which were satisfactory reproduced by a kinetic simulation including the relaxation of hot HCO radicals. These experimental, theoretical, and modeling results provide solid evidence for the prompt dissociation of hot HCO radicals formed in the C 2 H 3 + O 2 reaction. The product‐specific rate constants that extrapolated to higher temperature and wider pressure ranges are presented. Implications of the suggested mechanism for combustion modeling are also discussed.