• Kasigkeit, C.; Hirsch, K.; Langenberg, A.; Möller, T.; Probst, J.; Rittmann, J.; Vogel, M.; Wittich, J.; Zamudio-Bayer, V.; von Issendorff, B.; Lau, J.T.: Higher Ionization Energies from Sequential Vacuum Ultraviolet Multiphoton Ionization of Size-Selected Silicon Cluster Cations. The Journal of Physical Chemistry C 119 (2015), p. 11148-11152

10.1021/jp511928m

Abstract:
The second to fifth ionization energies and the appearance sizes of the higher charge states of silicon clusters with 6–92 atoms are determined by sequential vacuum-ultraviolet multiphoton ionization of size-selected cluster ions in a cryogenic ion trap. The higher ionization energies are well described by the charging energy in a spherical droplet model. In contrast to the electron affinity and the first ionization energy of silicon clusters, the higher ionization energies seem to change less abruptly at the prolate-to-spherical shape transition.