Decay pathway determination of even-size dicationic silver clusters: Ag₁₆/²⁺ and Ag₁₈/²⁺ -revisited by pre-precursor selection and sequential decay

It is demonstrated how by selection of pre-precursor cluster ions Ag(2n-1)/²⁺ and collision-induced dissociation an ensemble of Ag(2n)/²⁺ can be produced, which is not contaminated by Ag(n)/⁺ clusters of the same size-to-charge state ratio, n/z. By use of this technique, Ag₁₆/²⁺ and Ag₁₈/²⁺ precursor ensembles have been prepared for further investigations. They are observed to decay by neutral monomer evaporation, Ag(2n)/²⁺→ Ag(2n-1)/²⁺ + Ag, and trimer fission, Ag(2n)/²⁺ → Ag(2n-3)/⁺ + Ag₃/⁺, and show no sign of symmetric fission. (C) 2000 Elsevier Science B.V.