SECONDARY CLUSTER ION DISTRIBUTIONS PRODUCED BY MEV ION IMPACTS ON GROUP IIA OXIDES AND NITRATES

Cluster ion distributions from MeV atomic ion impacts (fission fragmen ts from Cf-252 On divalent Group IIA (GIIA) oxides and nitrates have b een examined. The two predominant positive cluster species observed fr om both solids, (MOH+ and (MO)(n)M(+) (M denotes metal atom) are evide nce of a localized plasma state thought to be created by discrete MeV ion impacts. Cluster intensities and extent of clustering from nitrate s were generally greater than those from oxides. The enhanced abundanc es at certain ''magic numbers'' of n observed in the mass spectra are believed to arise during the actual cluster production process. These periodic enhancements in cluster stabilities are attributed to the ado ption by size-specific clusters of atomic arrangements analogous to se gments of the rock salt lattice of the GIIA oxides. Cluster stabilitie s for the GIIA oxides and nitrates are influenced by the ionicity of M -O bonds, formal Valence of metal and radius of cation.