Reflection of Slow Electrons from Tungsten Single Crystals, Clean and with Adsorbed Monolayers

Abstract

The reflection of electrons with kinetic energy up to a few electron volts from tungsten single-crystal surfaces is measured both on the clean surface and with adsorbed monolayers of nitrogen and oxygen. For the clean surface, diffraction from the lattice is responsible for a considerable part of the reflection in the thermionic range of energy. The magnitude of the reflection is such as to have a barely measurable effect on experimental tests of the thermionic emission equations. This technique permits continuous recording of the change in work function as gas is adsorbed, yielding information about the kinetics of chemisorption and the surface dipoles due to the adsorbed gas atoms.