Ling Fengzi, Li Shuai, Song Xinli, Wang Yanmei, Long Jinyou, Zhang Bing
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2017 Nov 10;7(1):15362. doi: 10.1038/s41598-017-14483-w.
The butterfly vibration during the hydrogen tunneling process in electronically excited o-fluorophenol has been visualized in real time by femtosecond time-resolved ion yield spectroscopy coupled with time-resolved photoelectron imaging technique. A coherent superposition of out-of-plane C-F butterfly motions is prepared in the first excited electronic state (S). As the C-F bond vibrates with respect to the aromatic ring, the nuclear geometry varies periodically, leading to the corresponding variation in the photoionization channel. By virtue of the more favorable ionization probability from the nonplanar minimum via resonance with the Rydberg states, the evolution of the vibrational wave packet is manifested as a superimposed beat in the parent-ion transient. Moreover, time-resolved photoelectron spectra offer a direct mapping of the oscillating butterfly vibration between the planar geometry and nonplanar minimum. The beats for the photoelectron peaks originating from the planar geometry are out of phase with those from the nonplanar minimum. Our results provide a physically intuitive and complete picture of the oscillatory flow of energy responsible for the coherent vibrational motion on the excited state surface.
通过飞秒时间分辨离子产率光谱与时间分辨光电子成像技术相结合，实时观察到了电子激发态邻氟苯酚中氢隧穿过程中的蝴蝶振动。在第一激发电子态（S）中制备了面外C-F蝴蝶运动的相干叠加。当C-F键相对于芳环振动时，核几何结构周期性变化，导致光电离通道相应变化。由于通过与里德堡态共振，从非平面极小值处有更有利的电离概率，振动波包的演化在母离子瞬态中表现为叠加拍频。此外，时间分辨光电子能谱直接映射了平面几何结构和非平面极小值之间振荡的蝴蝶振动。源自平面几何结构的光电子峰的拍频与源自非平面极小值的拍频相位相反。我们的结果提供了一幅关于激发态表面上相干振动运动所涉及的能量振荡流的直观且完整的物理图像。
