Molecule emission from condensed Ar and O2 targets by 750Â eV Ne impact

The sputtering of a condensed Ar and a condensed O2 solid by 750 eV Ne+ ions is studied both by experiment and by molecular dynamics simulation. We focus on the emission of Ar2 dimers and O2 molecules. The translational energy distribution of ejected O2 molecules follows a high-energy fall-off ∼E−2 characteristic of collision-cascade ejection. Here simulation and experiment are in close agreement. The Ar2 translational energy distribution shows a steeper fall-off ∼En at high emission energies E with n∼4; it is interpreted to be due to the so-called recombination mechanism of dimer formation. These interpretations are corroborated by an analysis of the distance-of-origin of the emitted species. The role of three-body collisions on the Ar2 emission is discussed. A comparison of experimental and simulated energy distributions of sputtered Ar atoms and dimers allows us to identify a contribution of electronic sputtering of these species.