Fragmentation of small neutral carbon clusters

We report on theoretical and experimental efforts designed to understand the fragmentation of small neutral carbon clusters. Theoretically, the dissociation dynamics of Cn has been investigated using a statistical model based on the microcanonical Metropolis Monte Carlo method. In this model various structural quantities (geometries, dissociation energies, harmonic frequencies…) are required for both the parent cluster and the fragments. They have been obtained from quantum chemistry calculations for Cn up to n = 9. Experimentally, a new detection system for high velocity fragments has been recently developed allowing the fragmentation of high velocity clusters to be totally recorded. Results for the branching ratios of deexcitation of Cn with 5 ≤ n ≤ 9 formed by electron capture in high velocity Cn+–He collisions are presented. In all cases, the agreement between theory and experiment is reasonably good provided that the theoretical branching ratios are convoluted with a Cn energy distribution centered at around 10 eV.