Vibrating Atoms in Crystals

Abstract

Among the substances examined by Von Laue and his colleagues in 1912 was diamond; and Von Laue pointed out, without any particular emphasis because it was so obvious to him, that the reason why the diffraction pattern of diamond, unlike that of some other light-atom crystals, was still intense even in the back-reflection regions, was that the thermal vibrations of the atoms in diamond were exceptionally small. This recognition of the relationship between the vibration amplitude of atoms and the intensity of their scattering power has opened up a wide field of investigation, an investigation which is concerned with one essential difference between a solid, a liquid and a gas, that of movement. Since those early days many other research workers have interested themselves in this subject, notably Debye, Born, W. H. Bragg, Faxen, Waller, Laval, Preston, Zacha-Riasen, Raman, Wooster, Ubbelohde and the writer, their interests ranging from mathematical physics, through thermodynamics and the study of elasticity and plasticity to the simple observation of experimental X-ray scattering including effects not yet fully understood.