Satta Mauro, Catone Daniele, Castrovilli Mattea Carmen, Nicolanti Francesca, Cartoni Antonella
Institute of Nanostructured Materials-CNR (ISMN-CNR), Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185 Rome, Italy.
Istituto di Struttura della Materia-CNR (ISM-CNR), Area della Ricerca di Tor Vergata, Via del Fosso del Cavaliere, 00133 Rome, Italy.
Molecules. 2025 Feb 24;30(5):1029. doi: 10.3390/molecules30051029.
The reaction between methanol radical cations and methane, producing methyl radicals and protonated methanol, is pivotal to both astrochemical and atmospheric processes. Methanol and methane are the most abundant organic molecules in space and Earth's atmosphere and central to molecular synthesis under different environmental conditions. Here, we present a combined experimental and theoretical investigation of the ion-molecule reaction between CHOH and CH. The study explores the reaction mechanism and energetics under ionized conditions utilizing quantum chemical methods and experimental data. The findings reveal that the reaction's non-thermal behavior becomes pronounced when CHOH is vibrationally excited by photon absorption above the ionization threshold, as can happen in the presence of ionizing agents like cosmic rays. Conversely, in thermal equilibrium conditions, the reaction accelerates as temperatures decrease, as suggested by canonical rate coefficient calculations. The products can initiate further chemical reactions, shaping molecular networks in the interstellar medium and affecting atmospheric trace gas balances.
甲醇自由基阳离子与甲烷之间的反应生成甲基自由基和质子化甲醇，这对天体化学和大气过程都至关重要。甲醇和甲烷是宇宙空间和地球大气中最丰富的有机分子，并且是不同环境条件下分子合成的核心。在此，我们对CHOH⁺与CH₄之间的离子 - 分子反应进行了实验与理论相结合的研究。该研究利用量子化学方法和实验数据探索了电离条件下的反应机理和能量学。研究结果表明，当CHOH⁺通过吸收高于电离阈值的光子而发生振动激发时（如在存在宇宙射线等电离剂的情况下可能发生），反应的非热行为变得显著。相反，在热平衡条件下，如标准速率系数计算所示，反应随着温度降低而加速。这些产物可引发进一步的化学反应，塑造星际介质中的分子网络并影响大气微量气体平衡。
