Quantum effects in the trajectories of sputtered ions.

Abstract

Recent experimental results of Yu have shown remarkable behavior of the sputtering yield as a function of ion velocity. The usual assumption that the sputtered ions desorb as classical particles with a constant velocity is clearly incorrect at low velocities. We have tried a simple model based on a conjecture that the ion follows a quantum rather than a classical trajectory. The results, which are based on quasiclassical and quasistationary final-state ion trajectories (WKB wave functions with a complex potential), are in excellent agreement with the experiment. However, the imaginary part of the complex force necessary to achieve this agreement is at least an order of magnitude larger than typical interatomic forces. The conclusion therefore is that these quantum effects on the ion trajectory are not the cause of the nonlinearity of Yu's data.