Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, Madrid 28006, Spain.
Phys Chem Chem Phys. 2018 Oct 17;20(40):25951-25958. doi: 10.1039/c8cp04970j.
Is the rise of the rate constant measured in laval expansion experiments of OH with organic molecules at low temperatures due to the reaction between the reactants or due to the formation of complexes with the buffer gas? This question has importance for understanding the evolution of prebiotic molecules observed in different astrophysical objects. Among these molecules methanol is one of the most widely observed, and its reaction with OH has been studied by several groups showing a fast increase in the rate constant under 100 K. Transition state theory doesn't reproduce this behavior and here dynamical calculations are performed on a new full dimensional potential energy surface developed for this purpose. The calculated classical reactive cross sections show an increase at low collision energies due to a complex forming mechanism. However, the calculated rate constant at temperatures below 100 K remains lower than the observed one. Quantum effects are likely responsible for the measured behavior at low temperatures.
在低温下用有机分子进行的 OH 的激波膨胀实验中测量到的速率常数的增加是由于反应物之间的反应还是由于与缓冲气体形成复合物引起的？这个问题对于理解在不同天体物理物体中观察到的前生物分子的演化很重要。在这些分子中，甲醇是最广泛观察到的一种，其与 OH 的反应已被多个小组研究，表明在 100 K 以下速率常数快速增加。过渡态理论无法再现这种行为，因此在此针对此目的开发了一个新的全维势能表面来进行动力学计算。计算得到的经典反应截面在低碰撞能下由于复合物形成机制而增加。然而，在低于 100 K 的温度下计算得到的速率常数仍然低于观察到的速率常数。低温下的测量行为可能是由于量子效应引起的。
