title: Directly measuring reaction kinetics of ˙QOOH--a crucial but elusive intermediate in hydrocarbon autoignition.
abstract: Hydrocarbon autoignition has long been an area of intense fundamental chemical interest, and is a key technological process for emerging clean and efficient combustion strategies. Carbon-centered radicals containing an -OOH group, commonly denoted ˙QOOH radicals, are produced by isomerization of the alkylperoxy radicals that are formed in the first stages of oxidation. These ˙QOOH radicals are among the most critical species for modeling autoignition, as their reactions with O2 are responsible for chain branching below 1000 K. Despite their importance, no ˙QOOH radicals have ever been observed by any means, and only computational and indirect experimental evidence has been available on their reactivity. Here, we directly produce a ˙QOOH radical, 2-hydroperoxy-2-methylprop-1-yl, and experimentally determine rate coefficients for its unimolecular decomposition and its association reaction with O2. The results are supported by high-level theoretical kinetics calculations. Our experimental strategy opens up a new avenue to study the chemistry of ˙QOOH radicals in isolation.
authors.affiliation: Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, CA 94551-0969, USA. jzador@sandia.gov
authors.forename: Judit
authors.initials: J
authors.lastname: Zádor
authors.forename: Haifeng
authors.initials: H
authors.lastname: Huang
authors.forename: Oliver
authors.initials: O
authors.lastname: Welz
authors.forename: Johan
authors.initials: J
authors.lastname: Zetterberg
authors.forename: David L
authors.initials: DL
authors.lastname: Osborn
authors.forename: Craig A
authors.initials: CA
authors.lastname: Taatjes