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

Previous investigations by instrumental neutron activation analysis of a variety of C-60, C-70 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 C-60 acid C-70 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 similar to 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. (C) 1998 Elsevier Science B.V. All rights reserved.