Effect of the x-ray beam collimation on the resolution of an energy dispersive diffractometer

Although the energy dispersive x-ray diffraction EDXD technique has proved to have several merits in comparison with its conventional angular dispersive counterpart, it has the serious drawback that its resolution is intrinsically lower than that of the latter. This makes EDXD unsuitable each time that high-resolution measurements are needed. However, a wide class of samples does not require high resolution since the diffraction peaks they produce are so wide that the further broadening due to the use of EDXD is negligible. Amorphous solids, liquids, semicrystalline materials, and nanocrystalline powders belong to such a category. In this case, it is not worth performing sophisticated simulations to calculate the angular transfer function of the diffractometer because a simplified model is sufficient to describe the effect of the angular divergence of the x-ray beam on peak broadening. The aim of the present work is to obtain an analytic function that can be used for this purpose, allowing the collimation system to be properly set up.