Macrocluster effect caused by single multiply charged ions: masses of gold nanoclusters (3–30 nm) arising as a result of electronic processes induced by fission fragment bombardment in ultradispersed targets of gold

Ultradispersed islet gold targets with mean sizes of islets within the range 5-20 nm are bombarded by Cf-252 fission fragments (FF) in the electronic stopping regime. As a result, gold nanoclusters are ejected from the targets. By means of a collector technique using transmission electron and scanning force microscopies (TEM and SFM), sizes and masses of the clusters are measured. It is shown that the clusters have a practically perfect spherical shape and that their size distributions are similar to those of islets on the targets. Taking into account the quasi-spherical shape of such gold islets the results obtained testify to a desorption mechanism involving the formation of free metal clusters within the nanometer size range (3-30 nm) as result of relaxation of the electron excitation created by single FFs in target islets and the target itself. (C) 1998 Elsevier Science B.V. All rights reserved.