Plastic flow induced by single ion impacts on gold

摘要

In situ TEM was used to follow RT irradiation of thinned bulk and 62nm thick gold films with Xe ions at 50-400 keV. Energy spikes from single ion impacts give rise to surface craters and holes which exist until annihilated by subsequent ion impacts. Video recording provided details with a time resolution of 33 ms. Craters were produced on the irradiated surface at all ion energies and on the opposite surface when the ions had enough energy to traverse the specimen. Crater sizes were as large as 12nm for the higher energy irradiations. On average, about 6% of impinging ions result in craters. A single 200 keV Xe ion may produce a hole in thin gold foils. Hole formation involves the movement by plastic flow of massive amounts of material, on the order of tens of thousand Au atoms per ion impact. Individual ion impacts also result in a filling of both holes and craters as well as a thickening of the gold foil. Change in morphology during irradiation is attributed to a localized, thermal-spike induced melting, coupled with plastic flow under the influence of surface forces.