Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction
Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction
复制标题
超快 X 射线衍射空间分辨率的基本限制
DOI：
--
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
P. Weber
中科院分区：
文献类型：
--
作者：
A. Kirrander;P. Weber
X射线自由电子激光使记录衍射图像的时间序列成为可能，以确定在超快光化学过程中分子几何结构的变化。使用最先进的三个分子(氘、乙烯和1，3-环己二烯)的模拟，我们证明了最初由泵浦激光制备的核波包的性质，以及它随后在沿反应路径传播时的色散，限制了结构动力学实验中所能获得的空间分辨率。波包的离域导致了在动量传递矢量Q较大时衍射信号的显著衰减，这一观测结果得到了一个简单的分析模型的支持。这表明，超过10-15A−1的高Q测量提供的实验回报很少，并且根据重复频率、光子通量和脉冲持续时间等参数确定实验的信噪比和时间分辨率的优先顺序可能是有利的。我们预计这些考虑因素将影响未来的实验设计，包括信号源开发和检测方案。
X-ray Free-Electron Lasers have made it possible to record time-sequences of diffraction images to determine changes in molecular geometry during ultrafast photochemical processes. Using state-of-the-art simulations in three molecules (deuterium, ethylene, and 1,3-cyclohexadiene), we demonstrate that the nature of the nuclear wavepacket initially prepared by the pump laser, and its subsequent dispersion as it propagates along the reaction path, limits the spatial resolution attainable in a structural dynamics experiment. The delocalization of the wavepacket leads to a pronounced damping of the diffraction signal at large values of the momentum transfer vector q, an observation supported by a simple analytical model. This suggests that high-q measurements, beyond 10–15 A − 1 , provide scant experimental payback, and that it may be advantageous to prioritize the signal-to-noise ratio and the time-resolution of the experiment as determined by parameters such as the repetition-rate, the photon flux, and the pulse durations. We expect these considerations to influence future experimental designs, including source development and detection schemes.
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DOI：
10.1063/1.4734313
发表时间：
2012-07
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Kenichiro Saita;D. Shalashilin
通讯作者：
Kenichiro Saita;D. Shalashilin
影响因子：
3.3
作者：
Makhov, Dmitry V.;Saita, Kenichiro;Shalashilin, Dmitrii V.
通讯作者：
Shalashilin, Dmitrii V.
走向结构飞秒化学动力学：空间和时间的成像化学。
影响因子：
3.4
作者：
Minitti MP
通讯作者：
Minitti MP
迈向超快光解离成像实验的完全量子建模。
影响因子：
3.4
作者：
Makhov DV
通讯作者：
Makhov DV