Chatterjee Ruchira, Weninger Clemens, Loukianov Anton, Gul Sheraz, Fuller Franklin D, Cheah Mun Hon, Fransson Thomas, Pham Cindy C, Nelson Silke, Song Sanghoon, Britz Alexander, Messinger Johannes, Bergmann Uwe, Alonso-Mori Roberto, Yachandra Vittal K, Kern Jan, Yano Junko
Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94704, USA.
LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
J Synchrotron Radiat. 2019 Sep 1;26(Pt 5):1716-1724. doi: 10.1107/S1600577519007550. Epub 2019 Aug 7.
This work has demonstrated that X-ray absorption spectroscopy (XAS), both Mn XANES and EXAFS, of solutions with millimolar concentrations of metal is possible using the femtosecond X-ray pulses from XFELs. Mn XAS data were collected using two different sample delivery methods, a Rayleigh jet and a drop-on-demand setup, with varying concentrations of Mn. Here, a new method for normalization of XAS spectra based on solvent scattering that is compatible with data collection from a highly variable pulsed source is described. The measured XANES and EXAFS spectra of such dilute solution samples are in good agreement with data collected at synchrotron sources using traditional scanning protocols. The procedures described here will enable XFEL-based XAS on dilute biological samples, especially metalloproteins, with low sample consumption. Details of the experimental setup and data analysis methods used in this XANES and EXAFS study are presented. This method will also benefit XAS performed at high-repetition-rate XFELs such as the European XFEL, LCLS-II and LCLS-II-HE.
这项工作表明，利用X射线自由电子激光（XFEL）的飞秒X射线脉冲，对毫摩尔浓度金属溶液进行X射线吸收光谱（XAS）分析，包括锰K边X射线吸收近边结构（XANES）和扩展X射线吸收精细结构（EXAFS）分析是可行的。使用两种不同的样品输送方法，即瑞利喷流和按需滴注装置，在不同锰浓度下收集了锰XAS数据。本文描述了一种基于溶剂散射的XAS光谱归一化新方法，该方法与从高度可变脉冲源收集的数据兼容。此类稀溶液样品的测量XANES和EXAFS光谱与使用传统扫描协议在同步辐射源收集的数据高度吻合。本文所述方法将能够在低样品消耗的情况下，对稀生物样品，特别是金属蛋白进行基于XFEL的XAS分析。介绍了本XANES和EXAFS研究中使用的实验装置和数据分析方法的详细信息。该方法也将有利于在欧洲XFEL、直线加速器相干光源二期（LCLS-II）和直线加速器相干光源二期高能量（LCLS-II-HE）等高重复率XFEL上进行的XAS分析。
