Encapsulated C60 in carbon nanotubes

Pulsed laser vaporization of graphite in the presence of certain metallic catalysts produces both carbon nanotubes and C60 molecules. In nanotube production, most of the C60 is removed, along with other residual contaminants, by purification and annealing. It has been suggested that C60 may be trapped inside a nanotube during this elaborate sequence, but this has not been detected.