Omezzine Gnioua Maroua, Swift Stefan J, Španěl Patrik
J Heyrovský Institute of Physical Chemistry of the CAS, v. v. i., Dolejškova 2155/3, 182 23 Prague 8, Czechia.
Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2/747, Prague 8, 180 00, Czechia.
Phys Chem Chem Phys. 2024 Oct 23;26(41):26585-26593. doi: 10.1039/d4cp03105a.
The kinetics of the reactions of HO, NO, O˙ and O˙ with -hexane, 3-methylpentane, 2,5-dimethylhexane and 2,3-dimethylheptane were studied experimentally under several selected ion flow tube (SIFT) conditions: in a Profile 3 instrument in He and N carrier gases at 300 K and in the Voice200 instrument in N carrier gas at 300 and 393 K - where the effect of the extraction lens voltage was also assessed. It was found that HO ions react differently than expected, with reaction rates slower than collisional. Instead of transferring a proton, they associate and form fragment product ions [M-H]. NO ions react hydride ion transfer. O˙ ions react charge transfer followed by fragmentation that is highly sensitive to the temperature and the ion extraction lens voltage. Negative ions did not react, except for the O˙ ion, which reacted an associative detachment process. Computational analysis using Density Functional Theory (DFT) provided insights into the exothermicities and exergodicities of these reactions. A notable result is that proton transfer from HO does not take place despite its potential exothermicity; this is important for the interpretation of proton transfer reaction (PTR) and SIFT mass spectrometry data.
在几种选定的离子流动管（SIFT）条件下，对HO、NO、O˙和O˙与正己烷、3 - 甲基戊烷、2,5 - 二甲基己烷和2,3 - 二甲基庚烷的反应动力学进行了实验研究：在Profile 3仪器中，于300 K的氦气和氮气载气中进行；在Voice200仪器中，于300 K和393 K的氮气载气中进行——其中还评估了提取透镜电压的影响。研究发现，HO离子的反应与预期不同，反应速率比碰撞速率慢。它们不是转移质子，而是缔合并形成碎片产物离子[M - H]。NO离子通过氢负离子转移进行反应。O˙离子通过电荷转移然后碎裂进行反应，该反应对温度和离子提取透镜电压高度敏感。除了O˙离子通过缔合脱离过程发生反应外，负离子不发生反应。使用密度泛函理论（DFT）进行的计算分析为这些反应的放热性和放能性提供了深入见解。一个显著的结果是，尽管HO质子转移可能放热，但该过程并未发生；这对于解释质子转移反应（PTR）和SIFT质谱数据很重要。
