In situ transmission electron microscopy has been used to observe sputtered Au during Xe ion irradiation in transmission geometry. The sputtered Au was collected on an electron transparent carbon foil. Nanoparticles were observed on the collector foil after they were ejected by single ion impacts. The ejection is from the melt zone formed during the thermal spike phase of a displacement cascade produced near the surface by a single ion impact. Such single ion impacts are also capable of producing craters. Ejected nanoparticles can make a significant contribution to sputtering.

• Received 7 June 2000

DOI:https://doi.org/10.1103/PhysRevLett.85.4968