An X-ray diffractometer for accurate structural invariant phase determination.

Instrumental advances and experimental procedures for determining invariant triplet phases by three-beam X-ray diffraction are presented. A simple X-ray diffractometer is described. It allows the exploitation of the natural linear polarization of synchrotron radiation for eliminating systematic errors in triplet-phase determination. Examples of data-collection procedures with the diffractometer for composing a polarization-dependent set of azimuthal scans are given as well as the suggestion of an analytical procedure for extracting accurate triplet phases.