The non-resonant neutralization dynamics of the multiply charged Rydberg ions escaping solid surfaces

Abstract

We investigate the intermediate and final population of the Rydberg states (nA ≫ 1, lA = 0 - 3, mA) of multiply charged ions escaping solid surfaces by using the two-state vector model. All our calculations have been carried out for intermediate projectile velocities (v ≈ 1 a.u.). The electron capture is non-resonant and characterized by the selective population of the ionic Rydberg states. The final population probabilities enable us to elucidate the role of the ionic core polarization and to analyze the nA, l A and v probability distributions. We consider the ions SVI, C1VII and ArVIII with core charges Z = 6,7 and 8, respectively, and the ions KrVIII and XeVIII with Z = 8. The model is applied on two different ion-surface systems in order to emphasize the influence of the solid work function. We discuss the appearance of resonances (pronounced maxima) in the probability distributions. The resonances are explained by means of the electron tunneling in the very vicinity of the ion-surface potential barrier top. It is demonstrated that the resonances are characteristic only for some combination of the surface and ionic characteristics (argon anomaly), in agreement with available beam-foil experimental data.