Ionization energies and stabilities of Nan, n<25: shell structure from measurements on cold clusters

M. L. Homer, J. L. Persson, E. C. Honea, R. L. Whetten

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49 Scopus citations


The stability patterns found in alkali-atomic clusters and their explanation in terms of electronic and structural factors have been controversial for some time. Generation of very cold Nan clusters in a novel source and use of a special photoion normalization method resolve the remaining questions by allowing precise determination of photoionization thresholds. This is demonstrated here for several sizes in the 7<n<26 range, where in two crucial cases the interpretations of earlier ionization threshold measurements on oven-beam clusters [M. Kappes, M. Schär, P. Radi, and E. Schumacher, J. Chem. Phys. 84, 1863 (1986)] disagreed with the explanation of the observed stability pattern. Combining the new values with the charged-cluster fragmentation energies of Bréchignac et al. [C. Bréchignac, P. Cahuzac, J. Leygnier, and J. Weiner, J. Chem. Phys. 90, 1492 (1989)] yields neutral cluster fragmentation energies that successfully account for the famous "magic-number" ledges [W.D. Knight, K. Clemenger, W.A. de Heer, W.A. Saunders, M.Y. Chou, and M.L. Cohen, Phys. Rev. Lett. 52, 2141 (1984)]. Our measurements offer decisive support for the applicability of the spherical/spheroidal electronic shell-model to smaller Nan clusters, even in their low-temperature form.

Original languageEnglish (US)
Pages (from-to)441-447
Number of pages7
JournalEuropean Physical Journal D
Issue number1
StatePublished - Mar 1991
Externally publishedYes


  • 36.40.+d

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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