Fragmentation of cluster ions in SIMS: cluster distributions over lifetime, excitation energy and kinetic energy release

Abstract

Ta n + clusters ( n≤8) have been produced by the sputtering of Xe + ions with energy of 9 keV. For sputtered clusters Ta n + (4≤ n≤8) the lifetime distributions and the internal energy distributions were determined. The average lifetimes and the average internal energies were obtained by the treatment of corresponding experimental distributions. The average internal energy per constituent atom is about ⋍ 1.8 ± 0.3 eV/atom and this value depends weakly on cluster size. The kinetic energy release (KER) distributions of the sputtered fragmented clusters were also measured. Within the framework of Klots's model of “evaporation ensemble” the dissociation energies of Ta n + (4≤ n≤7) clusters have been calculated by using KER-distributions.