Sputtering of condensed noble gases by keV heavy ions

Bombardment of condensed Kr and Xe by 2-8 keV noble gas ions results in very high sputtering yield. A considerable fraction (10-30%) of the sputtered particles consists of Van der Waals clusters, with Kr2, Kr3, Xe2, XeKr, XeKr2 and ArKr having been observed. The kinetic energy distributions of the sputtered monomer-species are in agreement with a collision cascade mechanism. However, at the low energy side an excess yield is observed. This is explained by a model which takes into account the large sputtering yields and the damage of the surface during the sputtering process. The energy distributions of the dimers and trimers are satisfactorily explained by a statistical model. It is concluded that the dimer and trimer species are sputtered during an early stage of the cascade. (orig.)