甲烷分子振动激发对与其相关反应动力学影响的研究

The chemical reaction usually needs energy. The effectiveness of energy in different degrees of freedom, such as translational energy, vibrational excitation, rotational excitation etc., in driving a chemical reaction is different, and the dynamics of the reaction is also dependent on the types of the driving energy. It is essential to understand the influence of the different types of the energy on the reactivity and dynamics of a chemical reaction in order to eventually control the chemical reaction. At current stage, we are still far from making useful control on chemical reactions at the microscopic level. However, the study of controlling chemical reactions often increase our understanding of how chemical reactions occur. Based on numerous studies on the chemical reactions, especially on the results of three atomic reactions, J. C. Polanyi proposed a set of rules which are the well-known “Polanyi’s rules” to explain the different roles played by the translational energy and the vibrational energy in driving chemical reactions. These rules can be used to explain most atom-plus-diatom reactions very well, however, some recent experimental results have shown that the extension of Polanyi’s rules to the polyatomic reactions is not very straightforward. In order to explore the general rules of the effects of different types of energy on the chemical reactivity and the dynamics for the polyatomic reactions, a systematic experimental investigations have to be carried out. In this proposal, using crossed-beam and time-sliced velocity map imaging techniques, two important elementary chemical reactions, CHD3(v1=1)+F and CHD3(v1=1)+O(1D), will be investigated in depth to explore how the vibrational excitation of reagents affects the chemical reactivity and the reaction dynamics. The results of these studies are believed to be helpful for us to figure out the general rules of polyatomic reaction dynamics.

化学反应的进行需要能量的驱动，不同形式的能量(平动能，振动激发，转动激发等)对于化学反应的驱动能力不同。研究和理解不同形式能量对于化学反应的反应性以及动力学的影响对于实现对化学反应的控制至关重要。在对一系列反应体系研究的基础上，J. Polanyi阐释了化学反应中平动能和振动能对于不同类型反应的反应性以及动力学的影响，即著名的“Polanyi法则”。该法则对于三原子反应体系适用得很好，但对于多原子分子反应体系而言，其不能简单地直接推广。因此，有必要针对重要的多原子分子反应体系进行深入的研究。本项目拟利用交叉分子束方法，结合时间切片离子速度成像技术对与甲烷分子相关的两个重要基元化学反应CHD3(v1=1)+F 与CHD3(v1=1)+O(1D)进行深入研究，以揭示甲烷分子的振动激发对这些反应的微观动力学过程的影响，为进一步从分子水平上理解复杂体系化学反应的机理提供坚实的科学依据。

化学反应的进行需要能量的驱动，不同形式的能量(平动能，振动激发，转动激发等)对于化学反应的驱动能力不同。研究和理解不同形式能量对于化学反应的反应性以及动力学的影响对于实现对化学反应的控制至关重要。在对一系列反应体系研究的基础上，J. Polanyi阐释了化学反应中平动能和振动能对于不同类型反应的反应性以及动力学的影响，即著名的“Polanyi法则”。该法则对于三原子反应体系适用得很好，但对于多原子分子反应体系而言，其不能简单地直接推广。因此，有必要针对重要的多原子分子反应体系进行深入的研究。本项目拟利用交叉分子束方法，结合时间切片离子速度成像技术对与甲烷分子相关的激元化学反应进行研究，以揭示甲烷分子的振动激发对这些反应的微观动力学过程的影响，为进一步从分子水平上理解复杂体系化学反应的机理提供坚实的科学依据。在本项目中，我们在1.21kcal/mol-9.00kcal/mol范围内，针对反应F+CHD3(v1=1)→HF+CD3进行了详细的实验研究。研究结果表明，在低碰撞能下，CH键的伸缩振动会使得激发态反应的反应性高于基态反应，随着碰撞能增高，激发态反应性逐渐降低，并最终低于基态反应的反应性，即此时CH键的伸缩振动激发会抑制反应的进行。另一方面，当反应初始总能量相同为9.8kcal/mol时，CH键的振动激发态反应的反应性与基态反应的反应性基本一致。