A multimode high-angular-resolution powder diffractometer

A new powder diffractometer has been designed which can be used for various experimental geometries such as the long-arm Bragg–Brentano method, Guinier method and parallel-beam method. The X-ray source, goniometer and scintillation counter are placed on rails so that the source-to-monochromator, monochromator-to-sample and sample-to-counter distances can be changed arbitrarily. A FWHM of 0.07° for the Kα₁ peak of the silicon 111 reflection was obtained by lengthening the counter arm in the Bragg-Brentano method. Rather high angular resolution was achieved by the Guinier and parallel-beam methods for organic samples having poor crystallinity and low absorption.