Real-time visualization of the vibrational wavepacket dynamics in electronically excited pyrimidine via femtosecond time-resolved photoelectron imaging
Real-time visualization of the vibrational wavepacket dynamics in electronically excited pyrimidine via femtosecond time-resolved photoelectron imaging
复制标题
通过飞秒时间分辨光电子成像实时可视化电子激发嘧啶中的振动波包动力学
DOI：
10.1063/1.4996207
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发表时间：
2017-07-28
影响因子：
4.4
通讯作者：
Zhang, Bing
中科院分区：
文献类型：
--
作者：
Li, Shuai;Long, Jinyou;Zhang, Bing
利用飞秒时间分辨光电子成像和时间分辨质谱，在真实的时间内观测了光激发嘧啶分子中S-1-T-1系间跃迁的振动波包动力学过程.利用波长为315.3nm的飞秒泵浦脉冲，制备了振动态的相干叠加，产生了振动波包。通过叠加在母离子瞬态上的持续量子拍频直接识别所制备的波包的组成，所述持续量子拍频具有与6a（1）和6 b（2）状态之间的能量分离一致的雅阁。振动波包的退相时间被确定为82 ps。更重要的是，可变的Franck-Condon因子之间的波包组件和分散的阳离子振动能级的实验说明，以确定暗态，并遵循飞秒时间尺度上的能量流动力学。来自6a（1）振动态的光电子峰的随时间变化的强度表现出清晰的量子拍频模式，其周期性与来自6 b（2）振动态的光电子峰相似，但相对于来自6 b（2）振动态的光电子峰有π rad的相移，从而提供了6a（1）/6 b（2）费米共振中受限的分子内振动能量再分配动力学的明确图像。由AIP出版社出版。
The vibrational wavepacket dynamics at the very early stages of the S-1-T-1 intersystem crossing in photoexcited pyrimidine is visualized in real time by femtosecond time-resolved photoelectron imaging and time-resolved mass spectroscopy. A coherent superposition of the vibrational states is prepared by the femtosecond pump pulse at 315.3 nm, resulting in a vibrational wavepacket. The composition of the prepared wavepacket is directly identified by a sustained quantum beat superimposed on the parent-ion transient, possessing a frequency in accord with the energy separation between the 6a(1) and 6b(2) states. The dephasing time of the vibrational wavepacket is determined to be 82 ps. More importantly, the variable Franck-Condon factors between the wavepacket components and the dispersed cation vibrational levels are experimentally illustrated to identify the dark state and follow the energy-flow dynamics on the femtosecond time scale. The time-dependent intensities of the photo-electron peaks originated from the 6a(1) vibrational state exhibit a clear quantum beating pattern with similar periodicity but a phase shift of pi rad with respect to those from the 6b(2) state, offering an unambiguous picture of the restricted intramolecular vibrational energy redistribution dynamics in the 6a(1)/6b(2) Fermi resonance. Published by AIP Publishing.