Ion screening in solids

The behavior of charged particle beams passing through gaseous or solid targets is discussed with regard to charge states of the emerging beams. For an ion moving slowly in condensed matter, the charge, over distances comparable to the interatomic spacing in the target, is completely screened out and the projectile behaves like a neutral atom. At higher velocities, the dynamic screening is reduced and the effective ionic charge rises with velocity. When the velocity exceeds all electron orbital velocities in the projectile, the ion moves as a stripped point charge. Phenomena depending on the interior of the moving ion are discussed, and extensive comparison of the theory is made with various empirical results. (21 figs, 1 table, 37 refs) (U.S.)