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24Methanol (CH3OH) is the simplest alcohol and is considered to be a future fuel, produced by 25 solar-driven reduction of carbon dioxide. The reaction of methanol and hydroxyl radicals is 26 important in both combustion and atmospheric systems because this reaction is the dominant 27 consumption pathway for methanol oxidation. Hydrogen abstraction at the CH3 or OH site of 28 CH3OH leads to different radical intermediates. The relative importance of these two channels 29 is critical for combustion modeling as the subsequent chemistries of the product radicals (CH3O 30 and CH2OH) are markedly different. In this work, we measured overall rate coefficients for the 31 reaction of methanol (CH3OH), methanol-d3 (CD3OH) and methanol-d1 (CH2DOH) Using our measured total rate coefficients, we determined site-specific H-abstraction rate 38 coefficients, and, hence, branching ratios of the two abstraction channels. Our results show that 39 abstraction at the CH3 site is the dominant channel, contributing more than 80% throughout our 40 temperature range. Our calculated site-specific rate coefficients (per H atom) over 900 -1300 41

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Hydroxyl radicals and olefins are quite important from combustion and atmospheric chemistry standpoint. Large amounts of olefinic compounds are emitted into the earth's atmosphere from both biogenic and anthropogenic sources. Olefins make a significant share in the tranportation fuels (e.g., up to 20% by volume in gasoline), and they appear as important intermediates during hydrocarbon oxidation. As olefins inhibit low-temperature heat release, they have caught some attention for their applicability in future advanced combustion engine technology. Despite their importance, the literature data for the reactions of olefins are quite scarce. In this work, we have measured the rate coefficients for the reaction of hydroxyl radicals (OH) with several diolefins,

Rapid multi-species sensing is an overarching goal in time-resolved studies of chemical kinetics. Most current laser sources cannot achieve this goal due to their narrow spectral coverage and/or slow wavelength scanning. In this work, a novel mid-IR dual-comb spectrometer is utilized for chemical kinetic investigations. The spectrometer is based on two quantum cascade laser frequency combs and provides rapid (4 µs) measurements over a wide spectral range (~1175–1235 cm−1). Here, the spectrometer was applied to make time-resolved absorption measurements of methane, acetone, propene, and propyne at high temperatures (>1000 K) and high pressures (>5 bar) in a shock tube. Such a spectrometer will be of high value in chemical kinetic studies of future fuels.