COLLISION-INDUCED DISSOCIATION OF DOUBLY-CHARGED STORED METAL CLUSTERIONS

Singly charged noble metal duster ions from an external laser vaporiza tion source are accumulated in a Penning trap. They are subjected to e lectron bombardment for further ionization. The doubly charged cluster s are size selected and their lour energy fragmentation pathways ore s tudied by multiple-collision-induced dissociation, The reaction produc ts are analysed by time-of-flight detection. In general, large cluster s fend to evaporate neutral atoms while small clusters fission into tw o singly charged fragments, one of which is a trimer. The details, how ever, vary and depend on the specific elements and cluster sizes as ex emplified by the fragmentation of doubly charged copper, silver, gold and platinum clusters of size around n = 16. (C) 1997 by John Wiley & Sons, Ltd.