A focusing crystal analyser for the rejection of inelastic X-ray scattering.
A focusing crystal analyser has been constructed that allows the rejection of inelastic X-ray scattering during diffuse scattering measurements close to an absorption edge. A Johann geometry was obtained by cylindrical bending of perfect silicon and germanium crystals. The choice of reflection, the effect of bending and the contribution of the source size are discussed in relation to the energy resolution. Measurements at the As K-edge (11.867 keV) and at the Cs K-edge (35.985 keV) are presented to demonstrate that the focusing analyser can be used over a wide energy range. A direct comparison with a flat perfect crystal with comparable energy resolution shows a gain in intensity by a factor of 50.