Electronic Spectroscopy and Dissociation Dynamics of Vinyl-Substituted Criegee Intermediates: 2-Butenal Oxide and Comparison with Methyl Vinyl Ketone Oxide and Methacrolein Oxide Isomers
Electronic Spectroscopy and Dissociation Dynamics of Vinyl-Substituted Criegee Intermediates: 2-Butenal Oxide and Comparison with Methyl Vinyl Ketone Oxide and Methacrolein Oxide Isomers
复制标题
乙烯基取代的 Criegee 中间体：2-丁烯醛的电子光谱和解离动力学以及与甲基乙烯基酮氧化物和甲基丙烯醛氧化物异构体的比较
DOI：
10.1021/acs.jpca.2c08025
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Lester, Marsha I.
中科院分区：
文献类型：
--
作者：
Wang, Guanghan;Liu, Tianlin;Zou, Meijun;Sojdak, Christopher A.;Kozlowski, Marisa C.;Karsili, Tolga N.;Lester, Marsha I.
2-丁烯醛氧化物Criegee中间体[（CH 3CH <$CH）CHOO]是异戊二烯臭氧分解产生的四碳不饱和Criegee中间体的异构体，其特征在于其第一个π* ← π电子跃迁和由此产生的解离动力学为O（1D）+ 2-丁烯醛[（CH 3CH <$CH）CHO]产物。在喷射冷却条件下观察到2-丁烯醛氧化物的电子光谱是宽的和非结构化的，其峰值吸收在373 nm处，在320和420 nm处跨越到半最大值，并且与计算的垂直激发能和其最低能量构象获得的吸收光谱良好的雅阁。通过O（1D）产物的速度图成像，确定了释放到产物的总动能的分布。大约一半的可用能量，推导出的理论计算的渐近能量，容纳作为内部激发的2-丁烯醛片段。一个简化的脉冲模型被引入到解释的光解动力学，它占2-丁烯醛氧化物和2-丁烯醛片段之间的几何变化，和振动激活的相关模式中的2-丁烯醛产品。应用简化的脉冲模型的光解异构甲基乙烯基酮氧化物揭示了更大的内部活化的甲基乙烯基酮产品所产生的甲基内旋转和岩石，这是明显不同的2-丁烯醛氧化物或甲基丙烯醛氧化物的解离动力学。
The 2-butenal oxide Criegee intermediate [(CH3CH═CH)CHOO], an isomer of the four-carbon unsaturated Criegee intermediates derived from isoprene ozonolysis, is characterized on its first π* ← π electronic transition and by the resultant dissociation dynamics to O (1D) + 2-butenal [(CH3CH═CH)CHO] products. The electronic spectrum of 2-butenal oxide under jet-cooled conditions is observed to be broad and unstructured with peak absorption at 373 nm, spanning to half maxima at 320 and 420 nm, and in good accord with the computed vertical excitation energies and absorption spectra obtained for its lowest energy conformers. The distribution of total kinetic energy released to products is ascertained through velocity map imaging of the O (1D) products. About half of the available energy, deduced from the theoretically computed asymptotic energy, is accommodated as internal excitation of the 2-butenal fragment. A reduced impulsive model is introduced to interpret the photodissociation dynamics, which accounts for the geometric changes between 2-butenal oxide and the 2-butenal fragment, and vibrational activation of associated modes in the 2-butenal product. Application of the reduced impulsive model to the photodissociation of isomeric methyl vinyl ketone oxide reveals greater internal activation of the methyl vinyl ketone product arising from methyl internal rotation and rock, which is distinctly different from the dissociation dynamics of 2-butenal oxide or methacrolein oxide.