THE REFLECTION OF SLOW ELECTRONS BY HYDROGEN-COVERED SINGLE CRYSTALS OF TUNGSTEN

Abstract

The fraction of the incident electrons reflected elastically from the (100), (211), (111), and (110) crystal faces of tungsten has been measured m the incident energy range 1–28 eV. The fraction reflected by the (100) and the (211) faces was changed dramatically by hydrogen adsorption. The size of this change and its variation with energy are comparable with the differential scattering of electrons by atomic hydrogen. The fraction reflected by the (111) surface was small and changed only slightly with hydrogen adsorption. No change was observed in the reflection of electrons from the clean (110) surface when it was exposed to hydrogen.The change in work function of the four faces on exposure to hydrogen has also been measured, and has been found to be large and positive for the (100) and the (211) surfaces, small and positive for the (111) face, and zero for the (110) surface.