• gas-phase collisions;
  • sputtering;
  • molecular dynamics simulation;
  • copper

We have performed molecular dynamic simulations of low-energy sputtering of copper by Ar atoms and estimated ionization probabilities of individual atoms. The trajectories of the sputtered copper atoms were investigated around the distance from the surface, where the charge state of the sputtered species is formed (the freezing distance). It was found that a large part of the sputtered atoms or ions undergoes near-surface gas-phase collisions after the charge state had been determined at freezing distances. The passage of the ions through the zone of collisions above the surface leads to a randomization of their freezing-distance velocities, which affects velocity distributions of both ions and neutral atoms. Copyright © 2012 John Wiley & Sons, Ltd.