Disintegration of ${\mathrm{C}}_{60}$ by heavy-ion irradiation

The changes in resistivity in fullerene (${\mathrm{C}}_{60}$) films subjected to 320-keV Xe ion irradiation are investigated as a function of ion dose. From a comparison of this dependence with similar data on Xe irradiated diamond and with data on C implanted fused quartz, it is concluded that upon ion impact ${\mathrm{C}}_{60}$ clusters completely disintegrate. This disintegration releases about 60 carbon atoms which disperse among the remaining intact ${\mathrm{C}}_{60}$ spheres giving rise to hopping conductivity between isolated C atoms. The present finding may explain the negative results in the search for fullerenes conjectured to exist in instellar dust and may establish limitations on the use of ion implantation to dope fullerenes with the aim of synthesizing new forms of high-${\mathit{T}}_{\mathit{c}}$ superconductors.