Sputtering of neutral clusters from silver-gold alloys

Polycrystalline Ag, Ag20Au80, Ag40Au60, Ag80Au20 and Au samples were bombarded with 15 keV Ar+ at 60° incidence and the resulting secondary neutral yield distribution was studied by non-resonant laser postionisation mass spectrometry. Neutral clusters containing up to 21 atoms were observed for the targets. The yield of neutral clusters, AgmAun−m, containing n atoms, Yn, was found to follow a power in n, i.e. Yn ∝ n−δ, where the exponent δ varied from 3.2 to 4.0. For a fixed n, the cluster yields showed a variation with number of gold atoms similar to that expected for a binomial distribution. In addition, the cluster compositions from the sputtered alloys were indicative of sputtering from a gold rich surface.