Potential sputtering from a Si surface by very highly charged ion impact

We have observed radiation effect in collision of slow highly charged ions with the following target materials; a SiO2 thin film, a Si(1 1 1)-(7 × 7) surface and a hydrogen terminated Si(1 1 1)-(1 × 1) surface. Secondary ion mass spectrometry and scanning tunneling microscopy revealed some features due to “potential sputtering”; (a) strong dependence of secondary particle emission on the surface condition, (b) high yield of positive ion emission including cluster fragments and (c) creation of nanometer sized surface structure. The mechanism for the potential sputtering is briefly discussed, based on the “Coulomb explosion” model.