Photochemistry of the Simplest Criegee Intermediate, CH2OO: Photoisomerization Channel toward Dioxirane Revealed by CASPT2 Calculations and Trajectory Surface-Hopping Dynamics.
Photochemistry of the Simplest Criegee Intermediate, CH2OO: Photoisomerization Channel toward Dioxirane Revealed by CASPT2 Calculations and Trajectory Surface-Hopping Dynamics.
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最简单的 Criegee 中间体 CH2OO 的光化学：CASPT2 计算和轨迹表面跳跃动力学揭示了通向二氧杂环丙烷的光异构化通道
DOI：
10.1021/acs.jpclett.8b00023
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发表时间：
2018-02
影响因子：
5.7
通讯作者：
Liu Fengyi
中科院分区：
文献类型：
--
作者：
Li Yazhen;Gong Qianqian;Yue Ling;Wang Wenliang;Liu Fengyi
Criegee中间体的光化学在大气化学中起着重要的作用，但与它们的热反应相比，它的研究相对较少。利用多参考CASPT 2电子结构计算和CASSCF轨道表面跳跃分子动力学，我们揭示了一个暗态参与的简单Criegee中间体（CH 2 OO）的A1 A → X1 A光异构化通道，导致环二环氧乙烷。A1 A态上的激发分子可能是通过B1 A → A1 A内部转换从B1 A态产生的，也可能是通过状态选择性电子激发形成的，它们被面外运动驱动向垂直的A/X1 A最小能量交叉点（MECI），然后无辐射衰变到基态，平均时间常数为138 fs，最终在254 fs形成二氧杂环丙烷。从A1 A态开始的动力学表明，从简单的Criegee中间体到二环氧乙烷的光异构化的量子产率为38%。A1 A → X1 A光异构化通道的发现有望拓宽Criegee中间体的反应性分布，加深对Criegee中间体光化学的理解。
The photochemistry of Criegee intermediates plays a significant role in atmospheric chemistry, but it is relatively less explored compared with their thermal reactions. Using multireference CASPT2 electronic structure calculations and CASSCF trajectory surface-hopping molecular dynamics, we have revealed a dark-state-involved A1A → X1A photoisomerization channel of the simple Criegee intermediate (CH2OO) that leads to a cyclic dioxirane. The excited molecules on the A1A state, which can have either originated from the B1A state via B1A → A1A internal conversion or formed by state-selective electronic excitation, is driven by the out-of-plane motion toward a perpendicular A/X1A minimal-energy crossing point (MECI) then radiationless decay to the ground state with an average time constant of ∼138 fs, finally forming dioxirane at ∼254 fs. The dynamics starting from the A1A state show that the quantum yield of photoisomerization from the simple Criegee intermediate to dioxirane is 38%. The finding of the A1A → X1A photoisomerization channel is expected to broaden the reactivity profile and deepen the understanding of the photochemistry of Criegee intermediates.