STRUCTURES AND FORMATION OF SMALL LACN+ METALLOFULLERENES

Injected ion drift tube techniques have been used to probe LaCn+ clust ers in the size range around LaC36+ where the fullerene cage becomes t oo small to accommodate a La atom. Mobility measurements show that as the fullerene cage shrinks, the La atom moves out of the cage into the carbon network, stabilizing clusters with an odd number of carbon ato ms. Annealing studies demonstrate that in this size range the presence of the La atom dramatically enhances the efficiency of conversion of bicyclic and monocyclic LaCn+ rings into fullerenes and graphite sheet s.