On mechanisms of sputtered ion emission

In this article certain concepts fundamental to the understanding of sputtered ion emission are discussed. The treatment of the escape probability of a surface-excited or ionized atom is examined in the context of three current models - the perturbation, bond-breaking and surface excitation models - and the conceptual relationships between these models are outlined. The surface photoelectron threshold is shown to be a key parameter in terms of which all three models address matrix effects, and it is shown that the variation of this parameter can account qualitatively for a wide range of matrix effects.