Theoretical studies of ion neutralization: A tight binding linear chain model

A tight binding semi-infinite chain is used to model the neutralization of ions impinging on a solid surface. Starting from the equations of motion for the appropriate annihilation operators of site-centered orbitals, two approaches to computing the neutralization probability are developed. The first approach is based on using the well-known molecular orbitals of such a chain. We conclude that this method, in general, is dependent on one's ability to obtain molecular orbitals for an extended solid system. The second approach developed is based on a Langevin-type model in that we separate out a primary zone where the collision of the ion with the surface occurs and treat the remainder of the chain by using a memory kernel. We conclude that this method offers hope for treating realistic systems. Numerical computations are carried out using both approaches for specific choices of the parameters of the model. Exact agreement between the methods is obtained. In addition, the neutralization probability is found to oscillate as a function of the incident ion energy. This behavior is analyzed in some detail as a function of the parameters of the model