CXXXIX. The physical nature of a metal surface in conduction theory

Abstract

Summary A metal electron striking the surface of the metal from inside will be reflected into the metal. In the present paper this process of reflection will be treated as a phenomenon of electron diffraction. The atoms in a metal surface form a regular array, and this array may be considered as a cross-grating. As all free electrons in a metal have practically the same (Fermi) energy, their wavelength is uniform, and the ratio between this wavelength and the cube-edge of a face- or body-centred cubic lattice can be calculated. This gives a relation between the electron wave-length and the dimensions of the cross-grating, and formulae for the distribution of intensity over the various orders of diffraction can be derived. The main result is that the specular reflection is generally suppressed over a wide range of angles of incidence. This is true for any angle between the crystal axes and the surface. Generally most of the intensity is deflected to the first order of diffraction, but in the case of glancing electrons (i.e. electrons striking the surface at very small angles) most of the reflected intensity is found at a direction almost perpendicular to the surface.