Kinetic Energy and Mass Analysis of Covalent Group Iv Cluster Ions in Pulsed-laser Stimulated Field Evaporation

Multiply charged cluster ions of silicon and carbon can be formed in pulsedlaser stimulated field evaporation. In general, the signal intensity decreases monotonically with the cluster size. However, a few cluster ion species stand out; these are species of greater stability. For Si, they are ~i," and ~i,", and for C they are c3+ and c5+. While Si field evaporates mostly as 2+ cluster ions, C field evaporates mostly as 1+ cluster ions. There is, however, a small fraction of 2+ and 3+ C-cluster ions. For 3+ C-cluster ions, the intensity is smaller for smaller cluster ion species, indicating the occurrence of Coulomb repulsive dissociation. The different stabilities observed for Si and C clusters are in good agreement with theoretical calculations.