Neutralization of keV-energy alkali-metal ions colliding at gold surfaces

Li⁺ and Na⁺ ions are scattered from Au(1 1 0) and Au(1 1 1) surfaces in the keV-energy range, respectively. The pronounced Li° and Na° fractions non-monotonically vary with incident energy and exit angle for high work function gold surfaces. In particular, the azimuthal angle dependence of Li° fraction has been observed at low incident energies for a grazing exit angle. The simple calculations are presented to compare with the experimental data. Our findings clearly indicate that both the perpendicular and parallel exit velocity affect the final neutral fraction.