In a perfect crystal, all of the individual molecules have the same conformation and orientation. When X-rays are focused through crystals of purified molecules, the rays are deflected by the atoms of the molecules in specific patterns, called diffraction patterns. The number of electrons in the atom determines the intensity of its scattering of x-rays.
Heavier atoms scatter more effectively.
A series of diffraction patterns are taken from several angles. These patterns provide the organizational information about the components of the molecules.