Origin of atomic clusters during ion sputtering - art. no. 207601

Previous studies have shown that the size distributions of small clusters ( n less than or equal to 40; n = number of atoms/cluster) generated by sputt ering obey an inverse power law with an exponent between -8 and -4. Here we report electron microscopy studies of the size distributions of larger clu sters (n greater than or equal to 500) sputtered by high-energy ion impacts . These new measurements also yield an inverse power law, but one with an e xponent of -2 and one independent of sputtering yield, indicating that the large clusters are produced when shock waves, generated by subsurface displ acement cascades, ablate the surface.