Modeling the Conformer-Dependent Electronic Absorption Spectra and Photolysis Rates of Methyl Vinyl Ketone Oxide and Methacrolein Oxide
Modeling the Conformer-Dependent Electronic Absorption Spectra and Photolysis Rates of Methyl Vinyl Ketone Oxide and Methacrolein Oxide
复制标题
DOI：
10.1021/acs.jpca.1c08381
复制
发表时间：
2022-01-20
影响因子：
2.9
通讯作者：
Karsili, Tolga N., V
中科院分区：
文献类型：
--
作者：
McCoy, Julia C.;Leger, Spencer J.;Karsili, Tolga N., V
克里基中间体是重要的大气氧化剂，由臭氧与释放到对流层的挥发性烯烃反应形成。小的克里基中间体（如ch260和CH3CHOO）是高活性的，通过单分子衰变或双分子化学去除它们主导了它们的大气寿命。随着Criegee中间体分子复杂性的增加，它们的电子吸收光谱在与对流层相关的太阳光谱内显示出深色偏移。在这些情况下，太阳能光解作用可能成为它们在大气中去除的竞争性贡献者。本文报道了两种四碳中心Criegee中间体甲基乙烯酮氧化物（MVK-oxide）和甲基丙烯醛氧化物（MACR-oxide）的构象依赖性模拟电子吸收光谱。mvk -氧化物和macr -氧化物都含有四个低能构象，它们在实验测量的光谱中是卷曲的。在这里，我们对每个构象进行反卷积，并估计四个构象对实验测量光谱的贡献。我们还估计了光解速率，并预测太阳能光解对于mvk -氧化物和macr -氧化物应该是一个更有竞争力的去除过程（参见ch260和CH3CHOO）。
Criegee intermediates are important atmospheric oxidants, formed via the reaction of ozone with volatile alkenes emitted into the troposphere. Small Criegee intermediates (e.g., CH2OO and CH3CHOO) are highly reactive, and their removal via unimolecular decay or bimolecular chemistry dominates their atmospheric lifetimes. As the molecular complexity of Criegee intermediates increases, their electronic absorption spectra show a bathochromic shift within the solar spectrum relevant to the troposphere. In these cases, solar photolysis may become a competitive contributor to their atmospheric removal. In this article, we report the conformer-dependent simulated electronic absorption spectra of two four-carbon-centered Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). Both MVK-oxide and MACR-oxide contain four low-energy conformers, which are convoluted in the experimentally measured spectra. Here, we deconvolute each conformer and estimate contributions from each of the four conformers to the experimentally measured spectra. We also estimate the photolysis rates and predict that solar photolysis should be a more competitive removal process for MVK-oxide and MACR-oxide (cf. CH2OO and CH3CHOO).