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

Two mechanisms of the charge state formation during secondary ion emis sion 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 condition s (type of metal, etc.) one of them can predominate. The calculated re sults agree quantitatively with the experimental data and are in favou r of the existence of a locally high electronic temperature in the col lision cascade area.