Thin polycrystalline films were bombarded with slow (less than 1keV) multi-charged (up to 9+) Ar ions, and the resultant total sputter yields were studied by using a quartz crystal micro-balance. It was noted that more than 99% of the sputtered particles were neutral and gave yields, at a given impact energy, that were proportional to the potential energy of the projectile ions. The associated potential sputtering process already took place far below an impact energy of 100eV. It could be related to defect production, following electron capture by the multi-charged ions, and removed about one LiF molecule per 100eV of projectile potential energy.

T.Neidhart, F.Pichler, F.Aumayr, H.P.Winter, M.Schmid, P.Varga: Physical Review Letters, 1995, 74[26], 5280-3