Inner-shell electron promotion in low energyLi+-Al(100) collisions

A previously unobserved inelastic excitation mechanism is reported for alkali ions scattered from a metal surface. Li 1s holes are generated via electron promotion during hard binary collisions with surface Al atoms. Excited Li then resonantly neutralizes to form ${\mathrm{Li}}^{\mathrm{*}}$ (1s 2${\mathit{s}}^2$). These particles autoionize above the surface and are thus detected as ions. At large scattering angles, the majority of the singly scattered ${\mathrm{Li}}^{+}$ ions participate in this promotion process for incident energies of ∼3 keV and higher.