Electron emission induced by multiply charged Ar ions impinging on a tungsten surface

Abstract

We have investigated collisions of Ar q+ ions on a clean polycrystalline tungsten surface at collision energies between 35 eV and 250 keV by analysis of the ejected secondary electrons. We report total electron yields as well as highly resolved energy spectra of electrons for different primary projectile charge states up to q = 12, for different collision energies and for different ejection angles. Special emphasis is given to the production mechanisms of electrons with energies above ≈ 100 eV. A relatively sharp structure near 212 eV, occurring for q ⩾ 8 predominantly at collision energies below ≈ 2 keV, is ascribed to Auger transitions in the neutralized projectile on its way to the surface. A broad structure between 125 and 175 eV, occurring predominantly at collision energies above ≈ 2 keV, can be interpreted as being due to target Auger processes, induced by vacancy transfer from the projectiles to the target atoms.