Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, 116024, P. R. China.
Phys Chem Chem Phys. 2018 Dec 5;20(47):29669-29676. doi: 10.1039/c8cp05920a.
The kinetics of the reaction of the simplest Criegee intermediate (CH2OO) with ammonia has been measured under pseudo-first-order conditions with two different experimental methods. We investigated the rate coefficients at 283, 298, 308, and 318 K at a pressure of 50 Torr using an OH laser-induced fluorescence (LIF) method. Weak temperature dependence of the rate coefficient was observed, which is consistent with the theoretical activation energy of -0.53 kcal mol-1 predicted by quantum chemistry calculation at the QCISD(T)/CBS//B3LYP/6-311+G(2d,2p) level. At 298 K, the rate coefficient at 50 Torr from the OH LIF experiment was (5.64 ± 0.56) × 10-14 cm3 molecule-1 s-1 while at 100 Torr we obtained a slightly larger value of (8.1 ± 1.0) × 10-14 cm3 molecule-1 s-1 using the UV transient absorption method. These experimental values are within the theoretical error bars of the present as well as previous theoretical results. Our experimental results confirmed the previous conclusion that ammonia is negligible in the consumption of CH2OO in the atmosphere. We also note that CH2OO may compete with OH in the oxidation of ammonia under certain circumstances, such as at night-time, high altitude and winter time.
最简单的 Criegee 中间体 (CH2OO) 与氨的反应动力学已通过两种不同的实验方法在准一级条件下进行了测量。我们在 50 Torr 的压力下，在 283、298、308 和 318 K 下使用 OH 激光诱导荧光 (LIF) 方法研究了速率系数。观察到速率系数的弱温度依赖性，这与量子化学计算在 QCISD(T)/CBS//B3LYP/6-311+G(2d,2p) 水平预测的 -0.53 kcal mol-1 的理论活化能一致。在 298 K 下，从 OH LIF 实验获得的 50 Torr 下的速率系数为 (5.64 ± 0.56) × 10-14 cm3 分子-1 s-1，而在 100 Torr 下，我们使用 UV 瞬态吸收法获得了稍大的值 (8.1 ± 1.0) × 10-14 cm3 分子-1 s-1。这些实验值在当前以及以前的理论结果的理论误差范围内。我们的实验结果证实了以前的结论，即在大气中 CH2OO 消耗过程中，氨可以忽略不计。我们还注意到，在某些情况下，例如在夜间、高海拔和冬季，CH2OO 可能与 OH 竞争氨的氧化。
