Rapid neutralization and charge equilibration of highly charged ions at grazing incidence on a surface

Abstract

We have measured the experimental final average charge states for ${\mathrm{C}}^{q+}$ $(q=2,4,6+),$ ${\mathrm{Ar}}^{q+}$ $(q=8,16,17+),$ and ${\mathrm{Fe}}^{q+}$ $(q=5,10,15,22+)$ ions grazingly reflected from a smooth graphite surface as a function of the initial charge state, impact angle, and impact velocity $(vl1\mathrm{a}.\mathrm{u}.).$ The final charge state is almost independent of the initial charge state of the ion and of the impact angle for all investigated ions and impact velocities, which indicates that the projectile experiences a charge-state equilibration during the grazing-angle collision. The velocity dependences of the average charge state after a grazing-angle collision and after foil penetration were found to be similar. However, the grazing-angle collision yields the lower average charge state. The three kinds of projectiles used in this work show similar properties during the scattering, despite their different electronic structures or masses, which suggests that our results can be generalized for any kind of highly charged ion.