The possibility of sputtering by point defects

Abstract
Fine structure has been observed in the time-of-flight spectra of atoms sputtered from the {100} surface of a gold crystal by 20 keV Ar+ ions. Sharp peaks are observed at 7 and 13 eV which account for > 10−2 atom/ion and which we cannot explain by existing collision models of sputtering. It is proposed that interstitial defects migrate to the surface, releasing part of their formation energy to eject atoms with well-defined energies.