State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China.
Science. 2013 Dec 20;342(6165):1499-502. doi: 10.1126/science.1246546.
Experimental limitations in vibrational excitation efficiency have previously hindered investigation of how vibrational energy might mediate the role of dynamical resonances in bimolecular reactions. Here, we report on a high-resolution crossed-molecular-beam experiment on the vibrationally excited HD(v = 1) + F → HF + D reaction, in which two broad peaks for backward-scattered HF(v' = 2 and 3) products clearly emerge at collision energies of 0.21 kilocalories per mole (kcal/mol) and 0.62 kcal/mol from differential cross sections measured over a range of energies. We attribute these features to excited Feshbach resonances trapped in the peculiar HF(v' = 4)-D vibrationally adiabatic potential in the postbarrier region. Quantum dynamics calculations on a highly accurate potential energy surface show that these resonance states correlate to the HD(v' = 1) state in the entrance channel and therefore can only be accessed by the vibrationally excited HD reagent.
先前，振动激发效率的实验限制阻碍了对振动能量如何在双分子反应中介导动力学共振作用的研究。在这里，我们报告了在 HD(v = 1) + F → HF + D 振动激发反应的高分辨率交叉分子束实验中，通过测量能量范围内的微分截面，在碰撞能为 0.21 千卡/摩尔 (kcal/mol) 和 0.62 kcal/mol 时，清楚地出现了两个向后散射 HF(v' = 2 和 3)产物的宽峰。我们将这些特征归因于在势垒后区域中被束缚在特殊的 HF(v' = 4)-D 振动绝热势能中的激发的 Feshbach 共振。在高度精确的势能表面上的量子动力学计算表明，这些共振态与入口通道中的 HD(v' = 1)态相关联，因此只能通过振动激发的 HD 试剂来访问。
