Scattering of Electrons by Stabnite and Galena

Abstract

A study has been made of the scattering of 20-60 kv electrons, produced in a hot cathode tube, by cleavage surfaces of stibnite and galena. The patterns from stibnite consist of spots, Kikuchi lines, bands, circles and parabolas. The spots are a surface grating effect with high resolving power for both surface directions. It is concluded that the crystal has relatively large mosaic units and that collisions with atoms, involving small energy losses, cause high absorption of the primary beam as it penetrates the crystal. Inelastic collisions, producing excitation of the thermal vibrations of the crystal, are considered. They cause increased scattering at angles just larger than the Bragg reflection angles and thus give a reason for the bands. The circles are considered to arise from localizing of an electron's wave packet to the neighborhood of a single row of atoms, a process initiated by an inelastic encounter with a single atom. The measurements indicate a potential difference of about 26 volts between the row of atoms and the outside of the crystal. The parabolas, which occur also with galena, are thought to be due to the confinement of an electron to a single plane of atoms.