Charge fraction measurements for 2.4-35 keV Arq+(q=2-13) projectiles backscattered from Au(110)

We report on measurements of absolute scattered projectile charge fractions for Arq+ ions (q = 2-13) with incident energies in the range 2.4-35 keV, t hat have been 120 degrees backscattered from Au(110) in quasi-binary collis ions. Use of a time-of-flight technique that incorporates a biased drift re gion permitted full separation of all scattered charged states, including n eutrals. At fixed projectile energy, the scattered ion fractions are relati vely independent of incident charge state until the projectile L-shell is o pened, at which point large enhancements are observed, amounting for 2+ sca ttered ions to more than a factor of twenty. For fixed projectile charge st ate, the scattered neutral fractions all decrease monotonically with increa sing energy, with the higher (q > 1) charge fractions showing a correspondi ng increase, while the q = 1 fractions initially rise to an extremum. and t hen fall off with yet higher incident energies. Comparisons are made with t he recent experimental results of Pesic et al.