Trajectory calculations of OH radical- and Cl atom-initiated reaction of glyoxal: atmospheric chemistry of the HC(O)CO radical.
Trajectory calculations of OH radical- and Cl atom-initiated reaction of glyoxal: atmospheric chemistry of the HC(O)CO radical.
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OH 自由基和 Cl 原子引发的乙二醛反应的轨迹计算：HC(O)CO 自由基的大气化学。
DOI：
10.1039/c0cp01942a
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
O. Setokuchi
中科院分区：
文献类型：
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作者：
O. Setokuchi
采用准经典轨道密度泛函方法研究了298 K下，由OH自由基和Cl原子引发乙二醛反应生成的HC（O）CO自由基的动力学. A ′ HC（O）CO自由基是在H原子夺取后立即形成的，它与最稳定的A″ HC（O）CO自由基之间的能量差估计为6.0 kcal mol（-1）.从A' HC（O）CO到A″ HC（O）CO弛豫后的剩余能量进入初生HC（O）CO自由基的内能，并迅速分解为HCO + CO。OH反应中分配到HC（O）CO自由基的平均内能高于Cl反应，这与反应的热力学性质一致。一小部分初生HC（O）CO自由基（91%的OH反应和47%的Cl反应）在2.5 ps内迅速分解成HCO和CO。剩余的HC（O）CO自由基不发生迅速分解，在O（2）存在下热分解或与O（2）加成。根据反应机理，重新评价了前两个实验中Cl原子引发反应产物产率比[CO]/[CO（2）]与[O（2）]（-1）的关系。两个结果分别给出了Cl原子引发反应的热分解速率为9.5 × 10（6）s（-1）和1.08 × 10（7）s（-1），迅速分解率为47%和41%，这与目前的轨迹计算结果吻合得很好.
On-the-fly quasi-classical trajectory calculations using the density functional method were carried out to investigate the dynamics of the HC(O)CO radical, formed by OH radical- and Cl atom-initiated reactions of glyoxal at 298 K. The energy difference between the A' HC(O)CO radical, formed immediately after H atom abstraction, and the most stable A″ HC(O)CO radical is estimated to be 6.0 kcal mol(-1). The surplus energy followed by relaxation from A' HC(O)CO to A″ HC(O)CO goes to internal energy of the nascent HC(O)CO radicals and causes prompt decomposition into HCO + CO. The average internal energy partitioned into the HC(O)CO radical is higher in the OH reaction than in the Cl reaction, in accordance with exothermicity of the reactions. A fraction of the nascent HC(O)CO radicals (91% for the OH reaction and 47% for the Cl reaction) promptly decomposes into HCO and CO within 2.5 ps. The remaining HC(O)CO radicals, which do not undergo prompt decomposition, decompose thermally or add with O(2) in the presence of O(2). I re-evaluated the previous two experiment results of the product yield ratio [CO]/[CO(2)] vs. [O(2)](-1) in the Cl atom-initiated reaction, in light of the reaction mechanism involving prompt decomposition. The two results give 9.5 × 10(6) s(-1) and 1.08 × 10(7) s(-1) for the thermal decomposition rate and 47% and 41% for the fraction of prompt decomposition in the Cl atom-initiated reaction, in good agreement with the present trajectory calculation.