Production and stability of silicon-doped heterofullerenes

Silicon-carbon binary clusters with various mean compositions are generated in a laser vaporization source from targets processed as mixtures of graphite and silicon powders. Their size distribution is first analyzed by time-of-flight mass spectroscopy, which shows the stability of carbon fullerenes doped with silicon atoms in substitutional sites. Further investigations on the level of silicon doping are carried out by means of the laser-induced fragmentation of selected sizes. The photoproduct size distributions give evidence for at least nine silicon atoms substituted into still stable fullerene networks. The synthesis of heterofullerenes is mainly assisted by the nucleation mechanisms from Si-C mixed atomic vapors. Just as in the case of externally doped fullerene precursors, the laser-induced annealing of stoichiometric silicon-carbide clusters appears as an alternative route to produce heterofullerenes in the gas phase.