Zhan Fei, Tao Ye, Zhao Haifeng
Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
J Synchrotron Radiat. 2017 Jul 1;24(Pt 4):818-824. doi: 10.1107/S1600577517005719. Epub 2017 May 18.
Time-resolved X-ray absorption spectroscopy (TR-XAS), based on the laser-pump/X-ray-probe method, is powerful in capturing the change of the geometrical and electronic structure of the absorbing atom upon excitation. TR-XAS data analysis is generally performed on the laser-on minus laser-off difference spectrum. Here, a new analysis scheme is presented for the TR-XAS difference fitting in both the extended X-ray absorption fine-structure (EXAFS) and the X-ray absorption near-edge structure (XANES) regions. R-space EXAFS difference fitting could quickly provide the main quantitative structure change of the first shell. The XANES fitting part introduces a global non-derivative optimization algorithm and optimizes the local structure change in a flexible way where both the core XAS calculation package and the search method in the fitting shell are changeable. The scheme was applied to the TR-XAS difference analysis of Fe(phen) spin crossover complex and yielded reliable distance change and excitation population.
基于激光泵浦/ X射线探测方法的时间分辨X射线吸收光谱（TR-XAS），在捕捉激发时吸收原子的几何和电子结构变化方面非常强大。TR-XAS数据分析通常在激光开启减去激光关闭的差分光谱上进行。在此，提出了一种用于扩展X射线吸收精细结构（EXAFS）和X射线吸收近边结构（XANES）区域中TR-XAS差分拟合的新分析方案。R空间EXAFS差分拟合可以快速提供第一壳层的主要定量结构变化。XANES拟合部分引入了一种全局非导数优化算法，并以灵活的方式优化局部结构变化，其中核心XAS计算包和拟合壳层中的搜索方法都是可变的。该方案应用于Fe（phen）自旋交叉配合物的TR-XAS差分分析，得到了可靠的距离变化和激发态布居数。
