Neutralization of noble-gas ions at very low energies

Neutralization of noble-gas ions (${\mathrm{He}}^{+}$, ${\mathrm{Ne}}^{+}$, ${\mathrm{Ar}}^{+}$) on Pt(100) has been studied. It is common to the three kinds of projectiles that the ion yield shows a V-shaped incident-energy dependence at very low energies. The minimum position of the yield and the steepness of the V shape depend on the projectile ion species. The ion-yield change is governed by the change of the ion survival probability against Auger neutralization. Angular distributions show that the ion yield becomes higher in small-angle scattering with decreasing incident energy. A new empirical model is presented for the ion survival probability depending on penetration depth and residence time in the ion-surface interaction region.