Temperature-Dependent Rate Coefficients for the Reaction of CH2OO with Hydrogen Sulfide

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• 作者：Mica C. Smith ; Wen Chao ; Manoj Kumar ; Joseph S. Francisco ; Kaito TakahashiJim Jr-Min Lin
• 刊名：Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：February 9, 2017
• 年：2017
• 卷：121
• 期：5
• 页码：938-945
• 全文大小：445K
• ISSN：1520-5215

文摘

The reaction of the simplest Criegee intermediate CH₂OO with hydrogen sulfide was measured with transient UV absorption spectroscopy in a temperature-controlled flow reactor, and bimolecular rate coefficients were obtained from 278 to 318 K and from 100 to 500 Torr. The average rate coefficient at 298 K and 100 Torr was (1.7 ± 0.2) × 10^–13 cm³ s^–1. The reaction was found to be independent of pressure and exhibited a weak negative temperature dependence. Ab initio quantum chemistry calculations of the temperature-dependent reaction rate coefficient at the QCISD(T)/CBS level are in reasonable agreement with the experiment. The reaction of CH₂OO with H₂S is 2–3 orders of magnitude faster than the reaction with H₂O monomer. Though rates of CH₂OO scavenging by water vapor under atmospheric conditions are primarily controlled by the reaction with water dimer, the H₂S loss pathway will be dominated by the reaction with monomer. The agreement between experiment and theory for the CH₂OO + H₂S reaction lends credence to theoretical descriptions of other Criegee intermediate reactions that cannot easily be probed experimentally.