  Au nanoparticles, prepared by thermal evaporation under high vacuum condition
on Si substrate, are irradiated with Au ions at different ion energies. During
ion irradiation, embedding of nanoparticles as well as ejection of
nano-clusters is observed. Ejected particles (usually smaller than those on the
Si substrate) due to sputtering are collected on carbon-coated transmission
electron microscopy (TEM) grids. Both the TEM grids and the ion-irradiated
samples are analyzed with TEM. Unirradiated as well as irradiated samples are
also analyzed by Rutherford backscattering spectrometry (RBS). In the case of
low energy (32 keV) ions, where the nuclear energy loss is dominant, both
sputtering and embedding are less compared to medium energy (1.5 MeV). In the
high energy regime (100 MeV), where the electronic energy loss is dominant,
sputtering is maximum but practically there is no embedding. Ion bombardment of
surfaces at an angle with respect to the surface-normal produces enhanced
embedding compared to normal-incidence bombardment. The depth of embedding
increases with larger angle of incidence. Au nanoparticles after ion
irradiation form embedded gold-silicide. Size distribution of the sputtered Au
clusters on the TEM grids for different ion energy regimes are presented.
