Instrument Function in Powder Diffraction

The instrument function for energy-dispersive powder diffraction and angular-dispersive powder diffraction is presented. The contribution made by sample absorption is included in the instrument function. Both the equatorial and axial divergence functions are calculated in reflection geometry. The axial divergence function is calculated for Soller slits and aperture slits. The equatorial aberrations and the absorption contributions to the line profile are determined for an apparatus with collimator, antiscatter and receiving slits.