Radioactive endohedral metallofullerenes formed by prompt gamma-generated nuclear recoil implosion

Previous investigations by instrumental neutron activation analysis of a variety of C60, C70 fullerenes and fullerene precursors have shown that these compounds contain non-negligible amounts of about 35 elemental trace impurities. These impurities may be distributed on the surface of the C60 and C70 samples and/or at some interstitial positions of the crystal lattice. Some of these impurity atoms can penetrate the fullerene cages by nuclear recoil during neutron irradiation. The recoiled atoms move with a large kinetic energy which they successively lose upon excitation and ionization on the atoms of the fullerene crystals. After reduction of the kinetic energy below ∼100 eV, this energy is enough for the atom to implode into the fullerene cages. Results are reported on the formation of some endohedral radioactive metal fullerenes.