Nonadiabatic transition (NAT) drives a variety of x-ray-induced photochemistry and photophysics used in nature and various fields. To clarify the x-ray-induced NAT dynamics, we performed nonadiabatic molecular dynamics simulations on electronically excited tropone (Tr) dications created by the carbon $KLL$ normal Auger decay. The Tr$^{2+}$ undergoes the NAT cascade via 10-10$^2$ states with time constants of 200-400 fs. We observed population traps in the highly excited states in 100 fs during the NAT cascade. The fingerprint of this population trap can be extracted from C($1s$) edge pump O($1s$) pre-edge probe femtosecond transient x-ray absorption spectra measured by the O($1s$) Auger electron yield method (TR-AEYS) using intense narrow band femtosecond x-ray free electron laser pulses. Our coupled ionization rate equation model demonstrates that selective and saturable C($1s$) core-ionization of Tr realizes background-free measurement. These results indicate that the importance of NAT in x-ray photochemistry and photophysics in large molecules. The real-time tracking of the NAT dynamics using TR-AEYS shall be a powerful approach for deeper insight.
Ultrafast Photodissociation Dynamics and Nonadiabatic Coupling Between Excited Electronic States of Methanol Probed by Time-Resolved Photoelectron Spectroscopy
通过对时间分辨光电子能谱学实验的详细分析和电子结构计算，研究了甲醇在156 nm光激发下的电子和核动力学.光激发泵浦脉冲之后是延迟的260 nm光电离探测脉冲，以产生通过速度图成像分析的光电子。质量分辨离子的产率，测量与类似的实验条件下，被发现表现出相同的时间依赖性作为特定的光电子能谱特征。能量分辨信号的起始和衰减时间从测量的光电子谱中提取，以实现高的时间分辨率，超过20 fs的泵浦和探测脉冲持续时间。当结合{ \it ab initio}计算选定的削减通过激发态势能面，这一信息允许动态的瞬态激发分子，表现出多个核和电子的自由度，以跟踪其固有的几个飞秒的时间尺度。在15 fs的光激发范围内，我们观察到了2 $^{1}$ A $''$（S $_2$）电子态与1 $^{1}$ A $'$（S $_3$）电子态的锥形交叉，揭示了原子核在C-O伸缩和C-O-H角打开后的光解路径.
Ultrafast Internal Conversion Dynamics Through the on-the-fly Simulation of Transient Absorption Pump-Probe Spectra with Different Electronic Structure Methods
Spectroscopic photorelaxation signatures in pyrazine from nonadiabatic dynamics simulations with coupled cluster theory
Norwegian University of Science and Technology（挪威科技大学）；European XFEL（欧洲XFEL）；Stanford University（斯坦福大学）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）
Multiple charge transfer driven complex reaction dynamics: covalent bonding meets van der Waals interactions
ShanghaiTech University（上海科技大学）；Shanghai Advanced Research Institute, Chinese Academy of Sciences（中国科学院上海高等研究院）；Institute of Applied Physics and Computational Mathematics（应用物理与计算数学研究所）；Goethe-Universität Frankfurt（法兰克福大学）
Conical Intersections Enable Ultrafast Molecular Spin Control in a Chromium Complex
Ningbo University（宁波大学）；Rosalind Franklin Institute（罗莎琳德·富兰克林研究所）；STFC Rutherford Appleton Laboratory（STFC鲁瑟福阿普尔顿实验室）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）；University of Toronto（多伦多大学）；University of Oxford（牛津大学）
A CASSCF/MRCI Trajectory Surface Hopping Simulation of the Photochemical Dynamics and the Gas Phase Ultrafast Electron Diffraction Patterns of Cyclobutanone
XMCQDPT2-Fidelity Transfer-Learning Potentials and a Wavepacket Oscillation Model with Power-Law Decay for Ultrafast Photodynamics
Department of Chemistry, Lomonosov Moscow State University（莫斯科大学化学系）；MSU Institute for Artificial Intelligence, Lomonosov Moscow State University（莫斯科大学人工智能研究所）；Institute of Quantum Physics, Irkutsk National Research Technical University（伊尔库茨克国立研究技术大学量子物理研究所）
