Surface influences on resonant ionization during sputtering

The surface motion in resonant charge exchange processes, between a sputtered atom and a metal, has been representedby a simple mechanism in which diatomic molecular systems, formed transiently, in the collision cascade,generated by the primary bombardment, between secondary emitted and substrate atoms, may trap an electron into alocalized state. An Anderson±Newns Hamiltonian, containing both the atomic and the quasi-molecular levels, interactingresonantly and independently with the conduction band of the metal, has been adopted for evaluating the ®nalionized fraction in the outward atomic beam. Analytical calculations, including temperatures, have been performed onan interaction dynamics evolving over two di€erent time scales, related to the classical motion of the particles in thequasi-molecules. The velocity behavior of the ionized ¯ux has been obtained in a very simple case and its comparison toa SIMS experiment has provided interesting arguments ...