Scattered Si and fast recoiled Al are both present in time-of-flight spectra collected when 2.0 keV Si+ ions are incident on an Al(100) surface. Monte Carlo simulations were used to determine the origin of the spectral features, and electrostatic analysis was used to measure the ion yields and charge states as a function of the recoil and incident angles. The analysis indicates that all of the scattered Si projectiles are neutralized, while the recoiled Al is produced as neutrals and in singly, doubly, and triply charged states. The formation of multiply charged ions at this low energy is attributed to inner-shell promotion during the nearly symmetric Si-Al collision. Further experiments used Cl+ and SiCl+ projectiles for comparison. Multiply charged recoils were not observed with Cl+, while the behavior of SiCl+ could be interpreted as a linear combination of Si+ and Cl+ projectiles. (c) 2007 American Vacuum Society.