Symmetry of X-ray Intensities
The discussion of lattice symmetries leads to a general classification of the symmetry of intensity distributions in, e.g., X-ray photographs. Thus, if a unit cell is monoclinic and the lattice symmetry is 2/m then the symmetry of the diffraction intensities for this crystal will likewise be 2/m. In the X-ray photo below, the various reflections are related by rotation of 180° about the b* axis (b* is perpendicular to the plane of the figure).



This particular type of X-ray photo is taken with a precession camera, which provides an undistorted picture of the reciprocal unit cell.