Direct Kinetic Measurements of Criegee Intermediate (CH2OO) Formed by Reaction of CH2I with O2
Direct Kinetic Measurements of Criegee Intermediate (CH2OO) Formed by Reaction of CH2I with O2
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DOI：
10.1126/science.1213229
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发表时间：
2012-01-13
期刊：
影响因子：
56.9
通讯作者：
Taatjes, Craig A.
中科院分区：
文献类型：
--
作者：
Welz, Oliver;Savee, John D.;Taatjes, Craig A.
臭氧分解是对流层去除不饱和烃的主要机制，并通过“Criegee中间体”-羰基氧化物-在对流层氧化模型中发挥关键作用。然而，直到最近没有气相Criegee中间体已被观察到，并间接测定其反应动力学得到派生的速率系数跨越数量级。在这里，我们报告的直接光电离质谱检测甲醛氧化物（CH 2 OO）作为一个产品的反应CH 2 I与O-2。该反应使得能够直接实验室测定CH 2 OO动力学。上限提取与NO和H2O的反应速率系数。CH 2 OO与SO2和NO2的反应被证明是出乎意料的迅速，并意味着在对流层硫酸盐和硝酸盐化学模型中羰基氧化物的作用比以前假设的要大得多。
Ozonolysis is a major tropospheric removal mechanism for unsaturated hydrocarbons and proceeds via "Criegee intermediates"-carbonyl oxides-that play a key role in tropospheric oxidation models. However, until recently no gas-phase Criegee intermediate had been observed, and indirect determinations of their reaction kinetics gave derived rate coefficients spanning orders of magnitude. Here, we report direct photoionization mass spectrometric detection of formaldehyde oxide (CH2OO) as a product of the reaction of CH2I with O-2. This reaction enabled direct laboratory determinations of CH2OO kinetics. Upper limits were extracted for reaction rate coefficients with NO and H2O. The CH2OO reactions with SO2 and NO2 proved unexpectedly rapid and imply a substantially greater role of carbonyl oxides in models of tropospheric sulfate and nitrate chemistry than previously assumed.