Reflection and Diffraction of Slow Electrons from Single Crystals of Tungsten

Abstract

Measurements have been made of the elastic reflection coefficient and total secondary electron coefficient for electrons with energies from 1-206 eV incident normally on single crystals of tungsten (112), (100), and (110). The apparatus permitted visual observation of the full diffraction pattern in the same energy range. Ultra-high vacuum techniques were used. The major features of the elastic reflection coefficient for incident energies below 20 eV were found experimentally to be associated with the specularly reflected or 0-0 diffraction beam. A model based on superposition of atomic scattering was found to give a better over-all description of the observations than a model based on a potential varying only along the normal to the crystal.