Exoelectron emission from magnesium surfaces

Clean magnesium surfaces were created by evaporating Mg onto silicon wafers . When exposing the Mg surface to a low oxygen partial pressure, an exoelec tron emission (EEE) is observed after a time delay of the order of several hours after evaporation. On a much shorter time scale, similar effects in e xoemission from Mg and alkali metals have been observed previously. The res ults are discussed within a 'potential emission' model of exoelectrons duri ng oxygen capture at the pure Mg surface, but extending the model by includ ing an escape mechanism. A macroscopic quantitative description of the mode l is given, which is in good agreement with our measurements. (C) 1999 Else vier Science B.V. All rights reserved.