The Positions of Atoms in Metals

When a narrow beam of X-rays passes through a fine powder of any crystalline material, it produces on a photographic plate placed just behind the powder a pattern of concentric circles. These circles are produced by the reflection of the X-rays from the planes of atoms in the crystal, and their diameters are a measure of the distances between these planes of atoms. By measuring the diameters of the circles the exact positions of the atoms can be determined. The results of this analysis are given for twenty common metals and several salts, with examples and brief description of the method, and a discussion of the results.