Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
CNR-ISMN and Department of Chemistry, The University of Rome Sapienza, 00185 Rome, Italy.
J Phys Chem A. 2023 Jun 15;127(23):4919-4926. doi: 10.1021/acs.jpca.3c01402. Epub 2023 Jun 2.
We report on the three-body reaction rate of C with H producing CH studied in a cryogenic 16-pole radio frequency ion trap. The reaction was measured in the temperature range from 10 to 28 K, where it was found to only take place via three-body collisions. The experimentally determined termolecular rate coefficient follows the form of with = 20 K, where = 8.2(3) × 10 cm/s and = -0.82(12) denotes the temperature dependence. We additionally performed accurate calculations of the forces between the interacting partners and carried out variational transition state theory calculations, including tunneling through the barrier along the minimum energy path. We show that, while a simple classical model can generally predict the temperature dependence, the variational transition state theoretical calculations, including accurate quantum interactions, can explain the dominance of three-body effects in the molecular reaction mechanism and can reproduce the experimentally determined reaction coefficients, linking them to a temperature-dependent coupling parameter for energy dissipation within the transition complex.
我们报告了在低温 16 极射频离子阱中研究的 C 与 H 反应生成 CH 的三体反应速率。该反应在 10 到 28 K 的温度范围内进行了测量，发现仅通过三体碰撞发生。实验确定的三体速率系数遵循以下形式：其中 = 20 K，其中 = 8.2(3)×10 cm/s， = -0.82(12)表示温度依赖性。我们还进行了相互作用伙伴之间力的精确 计算，并进行了变分过渡态理论计算，包括沿着最小能量路径通过势垒的隧穿。我们表明，虽然简单的经典模型通常可以预测温度依赖性，但包括准确量子相互作用的变分过渡态理论计算可以解释三体效应在分子反应机制中的主导地位，并可以重现实验确定的反应系数，将它们与过渡复合物内能量耗散的温度相关联的耦合参数联系起来。
