科研之友
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摘要
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.
- 出版日期2012-3-14
