Projectile velocity and target temperature dependence of charge-state distributions of multicharged ions scattered during grazing interactions with a Au(110) surface.

Abstract

We have made systematic measurements of scattered projectile charge-state distributions for multicharged He, N, Ne, Na, and Ar ions grazingly incident on a Au(110) single-crystal target. For projectiles whose neutral binding energies Lie below the valence band (N, Ar, He, and Ne), observed 1+ charge fractions were small at low velocities and steeply increased above well-defined threshold velocities. However, for Na projectiles with neutral binding energy above the Fermi level, a large (about 84%) 1+ charge fraction was found. The velocity dependence of the Na neutral fraction shows a ''kinematic resonance'' due to the virtual population of electronic states above the Fermi level in the projectile rest frame. The measured sample temperature dependence of the scattered 1+ charge fraction for Ne9+ projectiles incident along the [110] surface channeling direction reveals a significant decrease in projectile neutralization once the (2X1)-(1X1) phase transition temperature of the Au(110) surface at 650 K has been reached.