Spence John C H, Zatsepin Nadia A, Li Chufeng
Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA
Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA.
Philos Trans R Soc Lond B Biol Sci. 2014 Jul 17;369(1647):20130325. doi: 10.1098/rstb.2013.0325.
The use of coherent X-ray lasers for structural biology allows the use of nanometre diameter X-ray beams with large beam divergence. Their application to the structure analysis of protein nanocrystals and single particles raises new challenges and opportunities. We discuss the form of these coherent convergent-beam (CCB) hard X-ray diffraction patterns and their potential use for time-resolved crystallography, normally achieved by Laue (polychromatic) diffraction, for which the monochromatic laser radiation of a free-electron X-ray laser is unsuitable. We discuss the possibility of obtaining single-shot, angle-integrated rocking curves from CCB patterns, and the dependence of the resulting patterns on the focused beam coordinate when the beam diameter is larger or smaller than a nanocrystal, or smaller than one unit cell. We show how structure factor phase information is provided at overlapping interfering orders and how a common phase origin between different shots may be obtained. Their use in refinement of the phase-sensitive intensity between overlapping orders is suggested.
将相干X射线激光用于结构生物学研究，能够使用具有大光束发散角的纳米直径X射线束。将其应用于蛋白质纳米晶体和单颗粒的结构分析，带来了新的挑战与机遇。我们讨论了这些相干会聚束（CCB）硬X射线衍射图样的形式，以及它们在时间分辨晶体学中的潜在用途，时间分辨晶体学通常通过劳厄（多色）衍射实现，而自由电子X射线激光的单色激光辐射并不适用于此。我们讨论了从CCB图样获得单次角度积分摇摆曲线的可能性，以及当光束直径大于或小于纳米晶体，或小于一个晶胞时，所得图样对聚焦光束坐标的依赖性。我们展示了如何在重叠干涉级次处提供结构因子相位信息，以及如何获得不同单次测量之间的公共相位原点。还建议了它们在重叠级次之间的相敏强度精修中的应用。
