title: Double and triple ionization of silver clusters by electron impact.
abstract: The production of silver cluster cations Ag(n)(2+) (for several selected sizes in the range n = 39-119) and Ag(n)(3+) (for n = 58, 61, 67) by electron impact ionization of neutral precursors has been studied. The scaling of appearance energies with cluster radius follows the metallic droplet model but, curiously, with a slope which is estimated to be quite different from the literature values for single ionization, Ag(n)(+), as well as for the appearance of smaller Ag(n)(2+) ions. It is also found that as the electron energy increases, the yield of high-charge cations grows faster than that of singly-charged Ag(n)(+). This behavior is consistent with the power-law dependence of post-threshold ionization. The mechanisms involved in multiple ionization phenomena in clusters of noble metals are not yet fully understood and call for further experimental and theoretical examination.
authors.affiliation: Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA.
authors.forename: Avik
authors.initials: A
authors.lastname: Halder
authors.forename: Anthony
authors.initials: A
authors.lastname: Liang
authors.forename: Chunrong
authors.initials: C
authors.lastname: Yin
authors.forename: Vitaly V
authors.initials: VV
authors.lastname: Kresin