The diffraction of electrons mercury vapour. —II

The interference of electrons is now a well established fact. It has been shown that when a homogeneous beam of electrons falls upon a regular arrangement of scattering centres, such as a crystal, a ruled grating, or a complex gaseous molecule, the angular distribution of the scattered electrons shows interference maxima and minima. The analagous, though distinct, phenomonon of the diffraction of electrons has, however, only recently been demonstrated. Evidence of the diffraction of electrons was first obtained about two years ago by Bullard and Massey, and the author. While investigating the angular distribution of elastically scattered electrons in mercury vapour I found well-marked maxima and minima. In this case the scattering was produced, not by an ordered arrangement of scattering centres, but by a random distribution of atoms. It has been shown theoretically that the results obtained can be satisfactorily explained on the assumption of scattering by a single centre, and consequently they represent a true diffraction effect.