Angular resolution of parallel foils on a synchrotron powder diffractometer.

In an attempt to improve the resolution in flat-plate diffraction geometry, a new set of parallel foils, 100 microm spacing, 365 mm long with an aperture of 20 x 20 mm(2), has been commissioned. The study was carried out using the two-circle diffractometer of station 2.3 at the SRS. In order to properly quantify the improvements, a detailed and comparative study of the instrumental resolution using the new and existing foils, of 200 micron spacing, is reported. A number of cubic materials, BaF2, Si and CeO2, that are known to show well defined Bragg peaks over the full 2theta angular range available, were investigated.