Testing Protocols for Obtaining Reliable Pair Distribution Functions from Laboratory X‐Ray Sources Using PDFgetX3

This work explores data acquisition and reduction protocols for atomic pair distribution scheme that enhances high-angle data collection, and the effects of instrumental parameters on resulting pair distribution functions are examined. A correction for sample absorption in PDFgetX₃ is introduced.

Herein, data acquisition protocols are explored and data reduction protocols are improved using PDFgetX3 to obtain reliable data for atomic pair distribution function (PDF) analysis from a laboratory-based Mo K _α 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. A Python script is presented that allows the comparison of PDFs obtained from different instruments and different acquisition protocols and does automatic uncertainty estimation and error propagation. A modification to the current PDFgetX3 data corrections to take care of sample absorption is also presented, which was previously neglected in the use of that program for high-energy synchrotron X-ray data.

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