Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, 69626, Villeurbanne, France.
Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232, Villigen, Switzerland.
Nat Commun. 2021 Jan 12;12(1):300. doi: 10.1038/s41467-020-20532-2.
Organic peroxy radicals (RO) play a pivotal role in the degradation of hydrocarbons. The autoxidation of atmospheric RO radicals produces highly oxygenated organic molecules (HOMs), including low-volatility ROOR dimers formed by bimolecular RO + RO reactions. HOMs can initiate and greatly contribute to the formation and growth of atmospheric particles. As a result, HOMs have far-reaching health and climate implications. Nevertheless, the structures and formation mechanism of RO radicals and HOMs remain elusive. Here, we present the in-situ characterization of RO and dimer structure in the gas-phase, using online tandem mass spectrometry analyses. In this study, we constrain the structures and formation pathway of several HOM-RO radicals and dimers produced from monoterpene ozonolysis, a prominent atmospheric oxidation process. In addition to providing insights into atmospheric HOM chemistry, this study debuts online tandem MS analyses as a unique approach for the chemical characterization of reactive compounds, e.g., organic radicals.
有机过氧自由基 (RO) 在烃类降解中起着关键作用。大气 RO 自由基的自动氧化产生了高度含氧的有机分子 (HOM)，包括由双分子 RO+RO 反应形成的低挥发性 ROOR 二聚体。HOM 可以引发并极大地促进大气颗粒的形成和增长。因此，HOM 对健康和气候有深远的影响。尽管如此，RO 自由基和 HOM 的结构和形成机制仍难以捉摸。在这里，我们使用在线串联质谱分析，对气相中的 RO 和二聚体结构进行了原位表征。在这项研究中，我们限制了由单萜臭氧分解产生的几种 HOM-RO 自由基和二聚体的结构和形成途径，单萜臭氧分解是一种重要的大气氧化过程。除了深入了解大气 HOM 化学之外，本研究还首次将在线串联 MS 分析作为一种独特的方法，用于对反应性化合物（例如有机自由基）进行化学表征。
