Fullerene genesis by ion beams III. On the absence of latent tracks in GeVion irradiated graphite

Irradiation of natural graphite with similar to 1 GeV lead and uranium ions initiates a phase change to fullerene (C-60) along the particle trajectori es. High resolution transmission electron microscopy (Dunlop ct al. [II) re veals no tracks in the bulk in either kinematic or diffraction contrast. Sm all amoeboid-like surface patches ale formed however, random in distributio n and proportional in number, but not equivalent to the total ion fluence. The evidence suggests that molecules of C-60 and other clusters are ejected from the entry and exit surfaces by electronic sputtering and are then dep osited. A mechanism referred to as particle activated prompt anneal (or PAPAf is pr oposed to explain the absence of latent tracks in the bulk. A reverse cooli ng and annealing wave permits recovery by epitaxy of the disorder and phase changes induced by the primary heat wave. Radiation enhanced recovery proc esses may also play a role. PAPA can additionally explain the absence of in duced fission fragment tracks in graphite, diamond, silicon and germanium.