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玻恩-奥本海默近似是量子化学以及化学动力学理论研究的重要基石之一,它对于化学反应过程中的动力学非常重要。但是在Cl+H2反应中该近似的适用性一直以来备受争议。本研究利用高灵敏度的交叉分子束实验,对Cl/Cl*+H2反应进行了交叉分子束反应散射的实验研究。实验结果表明激发态Cl*原子的反应性在低碰撞能下与基态的Cl原子的反应性相当,说明玻恩-奥本海默近似在低能时的适用性存在问题。但是,随着碰撞能量的增加,相对于基态Cl原子,Cl*原子与H2的反应快速下降,这表明在Cl+H2这一反应中玻恩-奥本海默近似在高碰撞能时是适用的。这一结果得到精确动力学理论研究的证实,而且解决了一个长期有争议的重要科学问题。
The Born-Oppenheimer approximation is one of the most important cornerstones of quantum chemistry and theoretical studies of chemical kinetics, and it is important for the kinetics of chemical reactions. However, the applicability of this approximation in the Cl + H2 reaction has long been controversial. In this study, a highly sensitive cross-molecular beam experiment was used to study the cross-molecular beam scattering of Cl / Cl * + H2 reaction. Experimental results show that the reactivity of the excited state Cl * atoms is comparable with that of the ground state Cl atoms at low collision energy, which indicates that the applicability of the Born-Oppenheimer approximation at low energy is problematic. However, as the collision energy increases, the reaction of Cl * atoms with H2 decreases rapidly with respect to the ground state Cl atoms, indicating that Born-Oppenheimer approximation is suitable for high collision energy in the Cl + H2 reaction of. This result is corroborated by studies of precise kinetic theory and has solved a major scientific issue that has long been controversial.