SPUTTERING OF NEUTRAL AND IONIC INDIUM CLUSTERS

Secondary neutral and secondary ion cluster yields were measured durin g the sputtering of a polycrystalline indium surface by normally incid ent approximately 4 keV Ar+ ions. In the secondary neutral mass spectr a, indium clusters as large as In32 were observed. In the secondary io n mass spectra, indium clusters up to In18+ were recorded. Cluster yie lds obtained from both the neutral and ion channel exhibited a power l aw dependence on the number of constituent atoms n in the cluster, wit h the exponents measured to be -5.6 and -4.1, respectively. An abundan ce drop was observed at n = 8, 15, and 16 in both the neutral and ion yield distributions, suggesting that the stability of the ion (either secondary ion or photoion) plays a significant role in the observed di stributions. In addition, our experiments suggest that unimolecular de composition of the neutral cluster may also play an important role in the measured yield distributions.