Caleman Carl, Tîmneanu Nicuşor, Martin Andrew V, Jönsson H Olof, Aquila Andrew, Barty Anton, Scott Howard A, White Thomas A, Chapman Henry N
Opt Express. 2015 Jan 26;23(2):1213-31. doi: 10.1364/OE.23.001213.
In structural determination of crystalline proteins using intense femtosecond X-ray lasers, damage processes lead to loss of structural coherence during the exposure. We use a nonthermal description for the damage dynamics to calculate the ultrafast ionization and the subsequent atomic displacement. These effects degrade the Bragg diffraction on femtosecond time scales and gate the ultrafast imaging. This process is intensity and resolution dependent. At high intensities the signal is gated by the ionization affecting low resolution information first. At lower intensities, atomic displacement dominates the loss of coherence affecting high-resolution information. We find that pulse length is not a limiting factor as long as there is a high enough X-ray flux to measure a diffracted signal.
在使用强飞秒X射线激光进行结晶蛋白质结构测定时，损伤过程会导致曝光期间结构相干性的丧失。我们对损伤动力学采用非热描述来计算超快电离和随后的原子位移。这些效应在飞秒时间尺度上降低了布拉格衍射，并对超快成像进行了选通。这个过程取决于强度和分辨率。在高强度下，信号首先由影响低分辨率信息的电离进行选通。在较低强度下，原子位移主导影响高分辨率信息的相干性丧失。我们发现，只要有足够高的X射线通量来测量衍射信号，脉冲长度就不是一个限制因素。
