FRAGMENTATION OF CLUSTER IONS IN SIMS - CLUSTER DISTRIBUTIONS OVER LIFETIME, EXCITATION-ENERGY AND KINETIC-ENERGY RELEASE

Ta-n(+) clusters (n less than or equal to 8) have been produced by the sputtering of Xe+ ions with energy of 9 keV. For sputtered clusters T a-n+ (4 less than or equal to n less than or equal to 8) the lifetime distributions and the internal energy distributions were determined, T he average lifetimes and the average internal energies were obtained b y the treatment of corresponding experimental distributions. The avera ge internal energy per constituent atom is about similar or equal to 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 less than or equal to n less than or equal to 7) clusters have been calcul ated by using KER-distributions.