Electron-stimulated desorption of alkali-metal atoms and positive ions from alkali-metal layers adsorbed on oxidized tungsten and molybdenum surfaces

A survey is presented of the results on the ESD for alkali-metal ions and a toms from alkali-metal layers adsorbed on oxidized tungsten and molybdenum surfaces. The measurements have been carried out by means of a static magne tic mass spectrometer combined with a retarding field analyzer and employin g a time-of-flight method realized with a quadruple mass spectrometer, The neutral alkali-metal atoms desorbed from the surface have been ionized in a surface ionization detector. The ESD cross sections and energy distributio ns-for alkali-metal atoms and ions:have been measured as a function of the incident electron energy, the alkali-metal coverage, the substrate temperat ure and the degree of oxidation of the substrate. To interpret the results the Auger stimulated desorption model taking into account the-local surface field relaxation has been developed.