Kinetics of the gas phase reaction of the Criegee intermediate CH2OO with SO2 as a function of temperature.
Kinetics of the gas phase reaction of the Criegee intermediate CH2OO with SO2 as a function of temperature.
复制标题
Criegee 中间体 CH2OO 与 SO2 的气相反应动力学随温度的变化。
DOI：
10.1039/d1cp02932k
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Onel L
中科院分区：
文献类型：
--
作者：
Onel L
用时间分辨宽带紫外吸收光谱研究了CH2I2/O2/SO2/N2混合物在248 nm处的闪光光解反应，研究了CH2I2/O2/SO2/N2混合物在223-344K温度范围内与SO2的气相反应动力学。测量是在SO2的伪一级条件下进行的，揭示了负的温度依赖关系。使用多能井反应主方程求解器(MESMER)对实验结果的分析表明，观察到的温度依赖关系，加上报道的在1.5-760Torr范围内缺乏压力依赖关系，可以用一个反应机理来描述，该反应机理包括形成反应前的络合物，导致环状次级臭氧化合物随后分解，生成HCHO+SO3。其温度依赖关系可用KCH2OO+SO2=(3.72±0.13)×10−11(T/298)(−2.05±0.38)−1 S−1表征。在较低温度下观察到的标题反应的负温度依赖关系以及水二聚体(Criegee中间体的主要竞争对手)浓度的降低意味着Criegee中间化学在较低温度下对大气中SO2的氧化起到增强作用。
The kinetics of the gas phase reaction of the Criegee intermediate CH2OO with SO2 have been studied as a function of temperature in the range 223–344 K at 85 Torr using flash photolysis of CH2I2/O2/SO2/N2 mixtures at 248 nm coupled to time-resolved broadband UV absorption spectroscopy. Measurements were performed under pseudo-first-order conditions with respect to SO2, revealing a negative temperature dependence. Analysis of experimental results using the Master Equation Solver for Multi-Energy well Reactions (MESMER) indicates that the observed temperature dependence, combined with the reported lack of a pressure dependence in the range 1.5–760 Torr, can be described by a reaction mechanism consisting of the formation of a pre-reaction complex leading to a cyclic secondary ozonide which subsequently decomposes to produce HCHO + SO3. The temperature dependence can be characterised by kCH2OO+SO2 = (3.72 ± 0.13) × 10−11 (T/298)(−2.05±0.38) cm3 molecule−1 s−1. The observed negative temperature dependence for the title reaction in conjunction with the decrease in water dimer (the main competitor for the Criegee intermediate) concentration at lower temperatures means that Criegee intermediate chemistry can play an enhanced role in SO2 oxidation in the atmosphere at lower temperatures.