VELOCITY DEPENDENCE OF IONIZATION PROBABILITY OF SECONDARY IONS EMITTED FROM METAL-SURFACES

Two mechanisms of the charge state formation during secondary ion emission from metals are shown to predominate: the tunneling one (resonant neutralization while the atomic level crosses the Fermi level of the metal) and the thermalization one (the establishment of the occupation of the atomic level corresponding to the local electronic temperature). Generally, both mechanisms are present, but under certain conditions (type of metal, etc.) one of them can predominate. The calculated results agree quantitatively with the experimental data and are in favour of the existence of a locally high electronic temperature in the collision cascade area.