The diffraction of electrons in the halogens

Abstract

Although the complete theory of the scattering of electrons by gas atoms must take into account the distortion of the incident and scattered waves by the atomic field, the exchange of electrons between the atom and the incident beam, and the disturbance of the atomic wave functions by the incident and scattered waves, a satisfactory explanation of the diffraction effects observed in the angular distribution of the elastically scattered electrons is obtained simply by considering the distortion of the incident wave by the undisturbed field of the atom. The scattering at large angles will then mainly depend upon the nature of the atomic field at the point in the atom where the potential energy of the incident electrons is equal to their kinetic energy. Now the magnitude and gradient of the field at any point within the atom at a distance r from the centre is determined mainly by the nuclear charge and the screening constants of the electrons within the radius r , and hence the nature of the field at a point well within the outer electron shell will be similar for atoms whose electronic structures differ only in the constitution of the outer shell.