CONICET | Buscador de Institutos y Recursos Humanos

The interaction of ions with solids is a complex process where several different basic physical mechanisms are involved. Auger process is the most usual mechanism of neutralization of the impinging ions where the Coulomb repulsion between two electrons in the solid forces one of them to tunnel, through the surface barrier, to fill the incoming hole. If the energy of this hole is larger than twice the solid work function, there is electron emission by Auger neutralization (AN). When the incoming ion level falls within the valence band, the neutralization is performed through a tunneling process without energy exchange, known as resonant neutralization (RN). He+/Al surface collision system is usually chosen as a model system for ion surface collision problems. Since the empty He+ ground state level falls below the bottom of the Al valence band, no resonant neutralization to this level is expected. However, a full quantum mechanical calculation of the neutralization probability applied to the LEIS regime based only on AN had shown major discrepancies with the experiments. The inclusion of resonant neutralization (RN) to He ground state and reionization (RI) processes, at close distances, improves the agreement between theory and experiment, but it is insufficient to explain the high He+ neutralization. In this work, a time-dependent quantum mechanical calculation including the neutralization to the ground and first excited states of He in a correlated way accordingly to a Coulomb blockade effect is performed. We found that the resonant neutralization to the He first excited state can improve the agreement between theory and ISS experiment in the He+/Al ISS experiments. On the other hand, the electron emission produced by the Auger deexcitation, following the neutralization to the He excited state, can account for the presence of energetic electrons in ion induced secondary electrons emission in the same system.