近日，中国科学院大连化学物理研究所杨学明团队研究了通过入口通道中的漫游机制增强syn-CH₃CHOO与H₂O的反应性。2025年4月16日出版的《自然-化学》杂志发表了这项成果。

Criegee中间体是高度反应性的物种，在大气化学中起着关键作用，对全球气候和空气质量产生了重大影响。它们是通过臭氧与烯烃的反应形成的，并通过其单分子分解和与关键大气成分的反应分别显著影响羟基自由基和气溶胶的形成。然而，它们与主要大气成分水蒸气的相互作用仍未得到充分表征。

研究组使用含时激光诱导荧光实验和全维动力学计算，研究了流行的Criegee中间体syn-CH₃CHOO与水蒸气的反应。该结果显示，反应速率比之前估计的要高得多，挑战了单分子分解主导顺式-CH₃CHO去除的传统观念。值得注意的是，他们发现了一种复杂的机制，涉及增强反应性的漫游过程。该发现需要对涉及合成单取代和二取代Criegee中间体与水的反应进行修订评估，这对于准确估算这些中间体的OH预算至关重要。

附：英文原文

Title: Reactivity of syn-CH3CHOO with H2O enhanced through a roaming mechanism in the entrance channel

Author: Liu, Yiqiang, Liu, Lijie, Fu, Yanlin, Jiang, Haotian, Wu, Hao, Liu, Yue, Lu, Xiaoxiao, Zhou, Xiaohu, Li, Hongwei, Skodje, Rex T., Wang, Xingan, Fu, Bina, Dong, Wenrui, Zhang, Dong H., Yang, Xueming

Issue&Volume: 2025-04-16

Abstract: Criegee intermediates are highly reactive species that play a pivotal role in the chemistry of the atmosphere, substantially impacting global climate and air quality. They are formed through the reaction of ozone with alkenes and considerably influence the formation of hydroxyl radicals and aerosols through their unimolecular decomposition and their reaction with key atmospheric components, respectively. However, their interaction with water vapour, a major atmospheric component, remains inadequately characterized. Here, using both time-dependent laser-induced fluorescence experiments and full-dimensional dynamics calculations, we investigate the reaction of syn-CH3CHOO, a prevalent Criegee intermediate, with water vapour. Our results reveal a much higher reaction rate than previously estimated, challenging the conventional notion that unimolecular decomposition dominates syn-CH3CHOO removal. Notably, we uncover a complex mechanism involving a roaming process that enhances reactivity. Our findings necessitate a revised assessment of reactions involving syn-mono- and di-substituted Criegee intermediates with water, which are crucial for accurately estimating the OH budget derived from these intermediates.

DOI: 10.1038/s41557-025-01798-9

Source: https://www.nature.com/articles/s41557-025-01798-9