In the context of tropospheric chemistry, Criegee intermediates denote carbonyl oxides with biradical/zwitterionic character (R1R2COO) that form during the ozonolysis of alkenes. First discovered almost 70 years ago, stabilised versions of Criegee intermediates formed via collisional removal of excess energy have interesting kinetic and mechanistic properties. The direct production and detection of these intermediates were not reported in the literature until 2008. However, recent advances in their generation through the ultraviolet irradiation of the corresponding diiodoalkanes in excess O2 and detection by various spectroscopic techniques (photoionisation, ultraviolet, infrared, microwave and mass spectrometry) have shown that these species can react rapidly with closed-shell molecules, in many cases at or exceeding the classical gas-kinetic limit, via multiple reaction pathways. These reactions can be complex, and laboratory measurements of products and the temperature and pressure dependence of the reaction kinetics have also revealed unusual behaviour. The potential role of these intermediates in atmospheric chemistry is significant, altering models of the oxidising capacity of the Earth's atmosphere and the rate of generation of secondary organic aerosol.

中文翻译：

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Criegee 中间体：生产、检测和反应性

在对流层化学的背景下，Criegee 中间体表示在烯烃的臭氧分解过程中形成的具有双自由基/两性离子特征 (R1R2COO) 的羰基氧化物。大约 70 年前首次发现，通过碰撞去除多余能量形成的稳定版本的 Criegee 中间体具有有趣的动力学和机械特性。这些中间体的直接生产和检测直到 2008 年才在文献中报道。 然而，通过紫外线照射过量 O2 中相应的二碘代烷烃和通过各种光谱技术（光电离、紫外线、红外线、微波和质谱）表明这些物质可以与闭壳分子快速反应，在许多情况下，通过多种反应途径达到或超过经典的气体动力学极限。这些反应可能很复杂，产品的实验室测量以及反应动力学的温度和压力依赖性也揭示了不寻常的行为。这些中间体在大气化学中的潜在作用非常重要，它改变了地球大气氧化能力和二次有机气溶胶生成速率的模型。