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

We report a collision-induced dissociation (CID) study of the stability 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 threshold energies have been extracted for each cluster size by fitting the 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, superimposed on an overall decrease in stability with increasing size. For most 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(+).