Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
J Chem Phys. 2019 Jan 28;150(4):044308. doi: 10.1063/1.5083681.
Coherent wavepacket motion in photoexcited pyrimidine has been initiated and visualized in real time using femtosecond time-resolved ion-yield spectroscopy. A coherent superposition of at least four low-frequency Frank-Condon (FC) active modes is created in the first excited electronic state (S), leading to a vibrational wavepacket. Its composition is manipulated experimentally by tuning the excitation wavelength in the range 309-313 nm to populate the selected vibrational levels. Interference among these vibrational levels is directly characterized by a clear quantum beat superimposed on a single-exponential decay. Fourier transform analysis of the wavelength-dependent transients shows modulation at different frequencies, providing a direct signature of multi-mode vibrational coherence resulting from the coherent excitation process. The sensitivity of the parent-ion transient to the vibrational wavepacket dynamics probably arises because different modes are connected by variable FC factors to the 3s and 3p Rydberg states.
利用飞秒时间分辨离子产量光谱学，我们实时启动并可视化了光激发嘧啶中的相干波包运动。在第一激发电子态 (S) 中创建了至少四个低频弗兰克-康登 (FC) 活性模式的相干叠加，导致了一个振动波包。通过在 309-313nm 的范围内调整激发波长来填充所选的振动能级，从而对其组成进行实验操作。这些振动能级之间的干涉通过叠加在单指数衰减上的清晰量子拍直接表征。对依赖于波长的瞬变的傅里叶变换分析显示出不同频率的调制，为相干激发过程产生的多模振动相干性提供了直接的特征。母离子瞬变对振动波包动力学的敏感性可能源于不同的模式通过可变的 FC 因子与 3s 和 3p 里德伯态相连。
