STABLE CONFIGURATIONS OF CARBON CLUSTERS - CHAINS, RINGS, AND FULLERENES

A systematic study of the size dependence of the vibrational modes of carbon clusters with 5-70 atoms is presented. The vibrational frequencies are measured using photoelectron spectroscopy of mass-separated negatively charged clusters. The clusters are carefully annealed. Only the most stable isomers are present in the beam after the annealing. Observed vibrational modes can be assigned to four dominant isomeric structures: linear chains (C5-, C7-, and C9-), monocyclic rings (C10-, C12-, C14-, C16-, and C18-), bicyclic rings (C20-, C24-, and C28-), and fullerenes (even n>C30-). © 1995 The American Physical Society.