Analysis of focused-beam powder X-ray diffraction resolution using doubly curved crystal optics

Abstract

In this work, focusing doubly curved crystal X-ray optics were used in powder diffraction to produce an intense spot for use with small powder or polycrystalline samples. Measurements of several standard small inorganic samples were made using a low-power microfocus source. Diffracted peak width, resolution and intensity were analyzed. The measured resolution, defined as the uncertainty in the peak center, was much smaller than the peak width, which was broadened owing to the use of a focused beam. Resolution was limited by the pixel size of the area detector. Resolution and intensity measurements were in good agreement with those obtained from simple geometric analysis and from a Monte Carlo model used to simulate the diffraction ring shape and width.