This Day in Science History - January 13 - Paul Niggli

January 13^th marks the passing of Paul Niggli. Niggli was a Swiss mineralogist who was a pioneer of x-ray crystallography. He developed the mathematical system of space groups that defined 230 different atom arrangements based on x-ray diffraction patterns. X-ray crystallography works by shining x-ray radiation through a crystal structure and detecting the interference pattern generated by the gaps between individual atoms. This information can tell you the position of atoms in a crystal, the width of atomic bonds, and even the size of the atoms themselves. All this information can give detailed help in determining the structure of a molecule. All that is really needed is a pure sample that can be crystallized.