Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction
Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction
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DOI：
10.1073/pnas.1805335115
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发表时间：
2018-06-26
影响因子：
11.1
通讯作者：
Mukamel, Shaul
中科院分区：
文献类型：
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作者：
Bennett, Kochise;Kowalewski, Markus;Mukamel, Shaul
由自由电子激光光源实现的超快时间分辨X射线散射，提供了关于分子中电子和核动力学过程的丰富信息。这项技术提供了传统上用于结构确定的随时间变化的电子电荷密度的频闪快照，并反映了弹性和非弹性过程、非绝热动力学以及电子布居和相干的相互作用。从核心共振和非共振衍射的角度考察了晶体中、气相或单分子中分子的布居和相干对超快非共振衍射的各种贡献。比较了单分子与N标度成正比和两分子与N-2标度成比例的贡献，其中N是活性分子的数量。对NaF中避开交叉处电子鱼叉的激发态非绝热动力学进行了模拟。我们展示了一类来自单个分子的多重衍射信号如何通过电荷密度的多维关联函数来揭示电荷密度的涨落。
Ultrafast time-resolved X-ray scattering, made possible by free-electron laser sources, provides a wealth of information about electronic and nuclear dynamical processes in molecules. The technique provides stroboscopic snapshots of the time-dependent electronic charge density traditionally used in structure determination and reflects the interplay of elastic and inelastic processes, nonadiabatic dynamics, and electronic populations and coherences. The various contributions to ultrafast off-resonant diffraction from populations and coherences of molecules in crystals, in the gas phase, or from single molecules are surveyed for core-resonant and off-resonant diffraction. Single-molecule proportional to N scaling and two-molecule proportional to N-2 scaling contributions, where N is the number of active molecules, are compared. Simulations are presented for the excited-state nonadiabatic dynamics of the electron harpooning at the avoided crossing in NaF. We show how a class of multiple diffraction signals from a single molecule can reveal charge-density fluctuations through multidimensional correlation functions of the charge density.