Coverage Dependence of the Neutralization Rate of an Ionized Adsorbate

TLDR: In this paper, a positive ion (ionized adsorbate) on atop position surrounded by a cluster of neutral adsorbates is placed on the (100) surface of a simple cubic crystal.

Abstract: A positive ion (ionized adsorbate) on atop position surrounded by a cluster of neutral adsorbates is placed on the (100) surface of a simple cubic crystal. An attractive Coulomb interaction between the ion and the metal atom directly below is explicitly included to prevent the ion from being quickly neutralized by electron transfer from the metal. No lateral interactions are placed at the outset, so that only indirect interactions through the metal (Rudeman-Kittel-type) enter. The degree of coverage (θ) is simulated by considering different clusters of neutral adsorbates and the ion line width, which controls the stimulated desorption ion yield, is calculated by a tight-binding Green function approach. It is found that the neutralization rate reaches a minimum (maximum ion yield) somewhere between θ = 1/4 and θ = 1/2 in agreement with experiment.