Observation of resonances in the transition state region of the F + NH3 reaction using anion photoelectron spectroscopy
Observation of resonances in the transition state region of the F + NH3 reaction using anion photoelectron spectroscopy
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DOI：
10.1038/s41557-022-01100-1
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发表时间：
2022-12-12
期刊：
影响因子：
21.8
通讯作者：
Neumark, Daniel M.
中科院分区：
文献类型：
--
作者：
Babin, Mark C.;DeWitt, Martin;Neumark, Daniel M.
化学反应的过渡态是反应物和生成物之间反应势能面（PES）上的一个分界面，因此对理解化学反应性具有重要意义。过渡态的瞬态性质对其实验表征提出了挑战。基于负离子光剥离的过渡态光谱实验可以直接探测PES的这一区域，揭示与过渡态相关的详细振动结构。这里我们研究了F + NH3 & RARR；低温冷却FNH3-阴离子HF + NH2反应的慢光电子速度图成像光谱研究。在全局PES上进行的降维量子动力学模拟与实验结果吻合良好，实现了光谱结构的分配。我们的实验与理论相结合的研究揭示了F + NH3 PES产物阱中存在多种振动费什赫共振。在更高的能量下，光谱识别出可能影响双分子反应动力学的跨过渡态和反应物配合物的局部共振特征。
The transition state of a chemical reaction is a dividing surface on the reaction potential energy surface (PES) between reactants and products and is thus of fundamental interest in understanding chemical reactivity. The transient nature of the transition state presents challenges to its experimental characterization. Transition-state spectroscopy experiments based on negative-ion photodetachment can provide a direct probe of this region of the PES, revealing the detailed vibrational structure associated with the transition state. Here we study the F + NH3 & RARR; HF + NH2 reaction using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled FNH3- anions. Reduced-dimensionality quantum dynamical simulations performed on a global PES show excellent agreement with the experimental results, enabling the assignment of spectral structure. Our combined experimental-theoretical study reveals a manifold of vibrational Feshbach resonances in the product well of the F + NH3 PES. At higher energies, the spectra identify features attributed to resonances localized across the transition state and into the reactant complex that may impact the bimolecular reaction dynamics.