The rates and outcomes of virtually all photophysical and photochemical processes are determined by Conical Intersections. These are regions of degeneracy between electronic states on the nuclear landscape of molecules where electrons and nuclei evolve on comparable timescales and become strongly coupled, enabling radiationless relaxation channels upon optical excitation. Due to their ultrafast nature and vast complexity, monitoring Conical Intersections experimentally is an open challenge. We present a simulation study on the ultrafast photorelaxation of uracil, which demonstrates a new window into Conical Intersections obtained by recording the transient wavepacket coherence during this passage with an x-ray free electron laser pulse. We report two major findings. First, we find that the vibronic coherence at the conical intersection lives for several hundred femtoseconds and can be measured during this entire time. Second, the time-dependent energy splitting landscape of the participating vibrational and electronic states is directly extracted from Wigner spectrograms of the signal. These offer a novel physical picture of the quantum Conical Intersection pathways through visualizing their transient vibronic coherence distributions. The path of a nuclear wavepacket around the Conical Intersection is directly mapped by the proposed experiment.
Exploring vibrational ladder climbing in vibronic coupling models: Toward experimental observation of a geometric phase signature of a conical intersection
Geometric phase effects in excited state dynamics through a conical intersection in large molecules: N-dimensional linear vibronic coupling model study
Topological origins of bound states in the continuum for systems with conical intersections
在具有圆锥交叉点（CI）的线性电子振动耦合模型中报道了连续体中的束缚态（BSC）[Cederbaum等人，Phys. Rev. Lett. 90，013001（2003）]。还发现这些状态在Born-Oppenheimer近似（BOA）内被破坏。我们调查是否一个非平凡的拓扑或几何相位（GP）与CI负责BSC。为了解决这个问题，我们探索修改原来的二维两态线性振动耦合模型支持BSC。这些修改要么在BOA之后添加GP效果，要么在两状态问题中删除GP。使用稳定图技术，我们表明，GP是至关重要的BSC的出现。
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）
Quantum mechanical and quasiclassical investigation of the time domain nonadiabatic dynamics of NO2 close to the bottom of the X2A1-A2B2 conical intersection
