ELECTRON-EMISSION YIELD FOR IMPACT OF SWIFT BARE LIGHT-IONS ON METALS

The electron emission yield induced by 0.5-8 MeV H+, He2+, Li3+, B5+ a nd C6+ impact on aluminum and gold targets was measured. The stopping power of bare ions is investigated. Stopping power values calculated a ccording to the Bethe term with and without Barkas and Bloch correctio ns and to the Z(2) scaling of hydrogen values are compared. The relati on of electron emission yield and the stopping power is explored. A si gnificant deviation of a proportionality of the yield to the stopping power is found. Using a - slightly modified - model by Borovsky and Su szcynsky [Phys. Rev. A 43 (1991) 1433] the experiments could be well r epresented. In this model the collective electric field generated alon g the projectile's path was taken into account. Consequently, the posi tive ion channel appears to be the dominant mechanism that leads beyon d a projectile independent yield/stopping power ratio.