EFFECT OF IMPURITY ON ION NEUTRALIZATION

The influence of a substitutional impurity atom on the ion neutralizat ion near the (100) surface of a simple cubic substrate is investigated using the Green's-function method. Ion neutralization is studied with in the framework of the approximate many-level method. The pure metal substrate is described by the three-dimensional tight-binding scheme, and the impurity is described by the Koster-Slater model. The effects of the impurity site, orbital energy, and impact site on ion neutraliz ation are discussed in detail. Calculations show that the ion occupanc y depends strongly on the impact site, and the impurity can play a pot entially dominant role in surface-ion neutralization.