SITE-SPECIFIC NEUTRALIZATION OF LOW-ENERGY LI-7(+) SCATTERED FROM NA AL(100)/

Site-specific neutralization is seen for low energy (1-5 keV) Li-7+ io ns scattered at large angles from Na-covered Al(100). Energy spectra o f the ion yield are collected near the surface normal as a function of Na coverage. Li+ singly scattered from Na is almost completely neutra lized, while the neutralization of ions scattered from Al is fairly in sensitive to coverage, indicating a large difference in the local elec trostatic potential above Na and Al sites. This shows that the phenome na of resonant charge exchange is capable of resolving atomic scale va riations in the surface potential.