Magic Numbers in a Mass Spectrum of Lithium Clusters Emitted from a Liquid Metal Ion Source

Abstract

Lithium ion clusters Li _n ⁺ with n ranging up to 19 have been observed from liquid lithium ion sources by using a magnetic mass analyzer. The ion intensity as a function of cluster size showed local maxima at n=7, 9, 13, and 19. Only n=9 and 19 can be explained by the electronic shell model, which successfully predicts magic numbers of other alkali metal (Na, K) clusters. On the other hand, the geometrical atom packing model explains the observed magic numbers except for n=9.