Liberation of Electrons by Fast Neutral Helium Atoms from a Tungsten Target

The electron emission from tungsten by bombarding helium atoms of energy ranging from 300 to 3500 ev has been measured for a surface with less than a monolayer and with multilayers of adsorbed gas. The yield expressed in electrons per particle rises almost linearly from about zero at 300 ev to 0.42 electrons/particle at 3500 ev for a monolayer of adsorbed gas. Further adsorption of gas gives a much increased yield. These yields are compared with the ion under like conditions. The distributions of the normal velocity and a component of the tangential velocity are compared for the ion and neutral atom on hot and cold targets.