Fragmentation of sputtered cluster ions of transition metals : distributions of lifetimes and internal energies

Dissociation energies, lifetime distributions and internal energies have been determined experimentally for Fe-n(+) (4 less than or equal to n less than or equal to 10) clusters produced by sputtering under 8.5 keV Xe+ ion bombardment. The average lifetimes and the average internal energies were calculated from the experimental distributions. A comparison between the results of the present work on Ta-n(+) and Nb-n(+) clusters and those obtained earlier has been made. For all sputtered clusters compared, the linear dependence of the average internal energy (E) over bar(int) on the number of atoms, n, in the cluster has been identified. Good qualitative agreement has been found between experimental results and theoretical values determined from MD-simulations of cluster sputtering processes

Discrimination and Quantification of Fe and Ni Abundances in Genesis 2 Solar Wind Implanted Collectors using X-ray Standing Wave 3 Fluorescence Yield Depth Profiling with Internal Referencing

X-ray standing wave fluorescence yield depth profiling was used to determine the solar wind implanted Fe and Ni fluences in a silicon-on-sapphire (SoS) Genesis collector (60326). An internal reference standardization method was developed based on fluorescence from Si and Al in the collector materials. Measured Fe fluence agreed well with that measured previously by us on a sapphire collector (50722) as well as SIMS results by Jurewicz et al. Measured Ni fluence was higher than expected by a factor of two; neither instrumental errors nor solar wind fractionation effects are considered significant perturbations to this value. Impurity Ni within the epitaxial Si layer, if present, could explain the high Ni fluences and therefore needs further investigation. As they stand, these results are consistent with minor temporally-variable Fe and Ni fractionation on the timescale of a year