Diffraction of partially coherent X-rays and the crystallographic phase problem

This paper proposes a new physical method for the partial solution of the c rystallographic phase problem by illuminating the crystal with an X-ray bea m of limited coherence. The diffraction spots broaden and, if the coherence length of the incident beam is small enough in all three dimensions, the d iffraction pattern becomes continuous. Independent information about the st ructure is then available both at the Bragg angles and at angles that do no t satisfy the Bragg conditions. Under certain conditions, the total informa tion is sufficient to solve the crystal structure ab initio. Two prescripti ons for producing X-ray beams with limited coherence are given.