Schulze-Briese C, Wagner A, Tomizaki T, Oetiker M
Swiss Light Source at Paul Scherrer Institute, Villigen, Switzerland.
J Synchrotron Radiat. 2005 May;12(Pt 3):261-7. doi: 10.1107/S0909049505003298. Epub 2005 Apr 14.
Cryocooled insulin and thaumatin crystals were irradiated in a series of alternating data collections and high-dose-rate exposures using either a vertically focused or vertically defocused beam. The main result is that the radiation damage is limited to the exposed region, which can be explained by the short range of the photoelectrons and the Auger electron cascade produced by light elements. Consequently, the unexposed angular range provides significantly improved data quality and electron density compared with previously exposed angular wedges of the crystal when a vertically focused beam is used, while no differences are observed between a fresh wedge and an exposed region for the vertically defocused beam. On the other hand, the focused beam provides higher I/sigma(I) ratios at high resolution than homogeneous sample illumination but also causes more rapid sample deterioration.
在一系列交替的数据收集和高剂量率曝光过程中，使用垂直聚焦或垂直散焦光束对低温冷却的胰岛素和奇异果甜蛋白晶体进行辐照。主要结果是，辐射损伤仅限于暴露区域，这可以用光电子的短程以及轻元素产生的俄歇电子级联来解释。因此，当使用垂直聚焦光束时，与晶体先前暴露的角楔形区域相比，未暴露的角范围提供了显著改善的数据质量和电子密度，而对于垂直散焦光束，新鲜楔形区域和暴露区域之间未观察到差异。另一方面，聚焦光束在高分辨率下比均匀样品照明提供更高的I/σ(I) 比值，但也会导致样品更快地劣化。
