低温下C + C6H6反应的动力学和氢原子产物研究
Kinetic and H-atom product study of the C + C6H6 reaction at low temperatures
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中文总结 AI 辅助
研究星际介质中C(3P) + C6H6反应，通过实验测定50 - 296 K速率常数及特定温度氢原子产率，结合天体化学建模测试其对相关物种丰度影响，揭示该反应是星际苯主要损失过程并讨论产物通道假说。
中文摘要 AI 辅助
基态电子构型的原子碳C(3P)反应在天体化学中可能是重要过程，因其在星际介质中丰度高且反应活性强。虽未在致密星际介质中检测到苯（C6H6），但通过其官能化衍生物推断其高丰度存在。本文对气相C(3P) + C6H6反应进行了实验和天体化学建模研究。实验上，用拉瓦尔喷嘴技术结合脉冲激光光解和激光诱导荧光分别测定C(3P)生成和检测的速率常数，在50 - 296 K范围内测定，还在177和296 K测量了氢原子产物产率。测得速率常数大，反应快速无势垒，氢原子产率低于C(3P) + C2H4参考反应。因该反应未纳入天体化学数据库，用致密星际云气粒模型测试其对C6H6及相关物种模拟丰度的影响。结果表明该反应是星际苯的主要损失过程，还在观测背景下讨论了产物通道假说以揭示优选形成途径。
英文摘要
The reactions of atomic carbon in its ground electronic state configuration, C(3P), are potentially important processes in astrochemistry due to the large abundance of C(3P) atoms in the interstellar medium (ISM) and its high overall reactivity towards a wide range of molecules. Although benzene, C6H6, has not been detected in the dense ISM, its presence at high abundance levels is inferred through the detection of functionalized derivatives. Here we present a combined experimental and astrochemical modeling investigation of the gas-phase C(3P) + C6H6 reaction. Experimentally, rate constants were determined over the 50-296 K range using the Laval nozzle technique coupled with pulsed laser photolysis and laser induced fluorescence for C(3P) generation and detection respectively. Product yields of atomic hydrogen, H(2S) were also measured at 177 and 296 K to provide some information on the product channels of the reaction. The measured rate constants are very large, between 3.3 and 5.7 x 10-10 cm3 s-1 indicating the fast, barrierless nature of the reaction, while the H-atom yields are all below 10 % when compared to the C(3P) + C2H4 reference reaction. As the C(3P) + C6H6 reaction is not currently included in astrochemical databases, its influence on the simulated abundances of C6H6 and related species was tested using a gas-grain model of dense interstellar clouds. The C(3P) + C6H6 reaction is shown to be the main loss process for interstellar benzene, while different hypotheses regarding the product channels are discussed in the context of observations to shed light on the preferred formation pathways.
