Characterization of N+n=2-18 clusters produced by 252Cf fission fragment impact on a N2 ice target

The structures and abundances of N-n = 2-18(+) clusters produced by impact of Cf-252 fission fragments (FF) on N-2 ice target are analyzed. A systematic search for the more stable conformers at the DFT/B3LYP level and a recently proposed methodology for a proper taxonomic description (D-plot) of the cluster isomers in series are presented. Several new members of the previously reported linear series have been identified. Besides that, three new series of clusters and some other stable structures have also been found. The clusters stability and ionization potential analysis showed that the Cf-252 FF exponential dependence of the cluster yield with its mass is rather a consequence of the production mechanism than that of the cluster structure. (C) 2007 Elsevier B.V. All rights reserved.