Testing Protocols for Obtaining Reliable PDFs from Laboratory x-ray Sources Using PDFgetX3

In this work, we explored data acquisition protocols and improved data reduction protocols using PDFgetX3 to obtain reliable data for atomic pair distribution function (PDF) analysis from a laboratory-based Mo x-ray source. A variable counting scheme is described that preferentially counts in the high-angle region of the diffraction pattern. The effects on the resulting PDF are studied by varying the overall count time, the use of Soller slits, and limiting the out-of-plane divergence of the incident beam. The protocols are tested using an amorphous silica and a quartz sample. We also present a modification to the current PDFgetX3 data corrections to take care of sample absorption, which was previously neglected in the use of that program for high-energy synchrotron x-ray data. We show that, despite limitations in the Q-range and flux of laboratory instruments, reasonable data for PDF model fits may be obtained using the best protocols in a few hours of counting.本研究探索了基于实验室钼X射线源的原子对分布函数（atomic pair distribution function, PDF）分析数据采集协议，并借助PDFgetX3工具优化了数据约简协议，以获取可靠的分析数据。本文描述了一种可变计数方案，该方案可优先对衍射图样的高角度区域进行计数。通过调整总计数时长、使用索勒狭缝（Soller slits）以及限制入射光束的面外发散角，研究了上述参数对最终PDF结果的影响。本研究采用无定形二氧化硅与石英样品对所提出的协议进行了验证测试。此外，我们针对当前PDFgetX3的数据校正流程提出了一项改进，用于处理样品吸收效应——此前在该程序用于高能同步辐射X射线数据时，该效应未被纳入考量。研究表明，尽管实验室级X射线仪器在Q范围与光子通量上存在局限，但通过采用最优协议，仅需数小时的计数时长即可获得可用于PDF模型拟合的可靠数据。