DISSOCIATION-ENERGIES FOR SMALL CARBON CLUSTER IONS (C-2-19(-INDUCED DISSOCIATION()) MEASURED BY COLLISION)

We report a collision-induced dissociation (CID) study of the stabilit y and fragmentation behavior of carbon cluster ions, C-n(+) (n = 2-19) . Measurements were made of the absolute CID cross sections, fragment appearance potentials, and fragment branching ratios. Dissociation thr eshold energies have been extracted for each cluster size by fitting t he data. The threshold energies fluctuate strongly with cluster size. Small clusters show strong even/odd alternations in stability, and the results are in good agreement with theoretical dissociation energies. For larger clusters a periodicity of four atoms is observed, superimp osed on an overall decrease in stability with increasing size. For mos t cluster sizes the dominant fragmentation channel is loss of C-3. For C-15(+), C-16(+), and C-19(+), loss of five atoms is a major channel, dominant in the case of C-16(+) and C-19(+).