Unimolecular HO2 Loss from Peroxy Radicals Formed in Autoxidation Is Unlikely under Atmospheric Conditions

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• 作者：Noora Hyttinen ; Hasse C. Knap ; Matti P. Rissanen ; Solvejg Jørgensen ; Henrik G. Kjaergaard ; Theo Kurtén
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：May 26, 2016
• 年：2016
• 卷：120
• 期：20
• 页码：3588-3595
• 全文大小：353K
• 年卷期：0
• ISSN：1520-5215

文摘

A concerted HO₂ loss reaction from a peroxy radical (RO₂), formed from the addition of O₂ to an alkyl radical, has been proposed as a mechanism to form closed-shell products in the atmospheric oxidation of organic molecules. We investigate this reaction computationally with four progressively oxidized radicals. Potential energy surfaces of the O₂ addition and HO₂ loss reactions were calculated at ROHF-RCCSD(T)-F12a/VDZ-F12//ωB97xD/aug-cc-pVTZ level of theory and the master equation solver for multienergy well reactions (MESMER) was used to calculate Bartis-Widom phenomenological rate coefficients. The rate coefficients were also compared with the unimolecular rate coefficients of the HO₂ loss reaction calculated with transition state theory at atmospheric temperature and pressure. On the basis of our calculations, the unimolecular concerted HO₂ loss is unlikely to be a major pathway in the formation of highly oxidized closed-shell molecules in the atmosphere.