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Kinetic Study on Reactions of 1- and 2-Methylvinoxy Radicals with O2

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journal contribution
posted on 22.12.2000, 00:00 authored by Tatsuo Oguchi, Akira Miyoshi, Mitsuo Koshi, Hiroyuki Matsui, Nobuaki Washida
The reactions of 1- and 2-methylvinoxy radicals with O2 have been studied by laser-induced fluorescence coupled with pulsed laser photolysis of precursor molecules at room temperature (298 ± 5 K). The rate constants for both reactions showed typical falloff pressure dependence in the investigated pressure range (8−330 Torr, He buffer), which suggests the dominance of recombination processes to form peroxy radicals. From the Rice−Ramsperger−Kassel−Morcus fit to the experimental data, the limiting high-pressure rate constants were derived to be k (1-methylvinoxy + O2) = 9.8 × 10-13 and k (2-methylvinoxy + O2) = 1.3 × 10-12 cm3 molecule-1 s-1, which are 5−7 times larger than that for the reaction of a nonsubstituted vinoxy radical. The influence of the methyl substituent effect and the resonance stabilization on the rate constants is discussed.