Cleavage patterns of carbon clusters from impact-induced fragmentation of C^-N, N = 10-50

The preferred fragmentation patterns of negatively charged carbon clusters, C^-N have been investigated by cluster-beam impact methods using various surfaces and impact energies (E_i = 0-150 eV). Transitions from one type of cluster structure to another are inferred from the observed change in fragmentation patterns. The results are made possible by the high intact-scattering yield of C^-N clusters, and by the competitiveness of fragmentation with electron emission for clusters N < 40. The main inferred structures and diagnostic fragmentation patterns are (i) chain structures (4 < N < 18), which fragment by C⁽⁰⁾₃ loss; (ii) ring structures, N ≈ 17-32, reflected by preferential cleavage to give large neutral clusters C⁽⁰⁾₁₄, and C⁽⁰⁾₂₂, (iii) polycyclic or cage structures, which shatter to yield an array of small fragments; and (iv) fullerene-type structures, N > 33, for which electron emission dominates over fragmentation. These results are compared and contrasted with results obtained from other fragmentation and collisional methods.