Fragmentation of fast positive and negative C60 ions in collisions with rare gas atoms

The fragmentation of C-60 anions and cations resulting from 50 keV collisions with rare gas targets is studied. Positive ion fragment patterns are recorded, and dramatic changes in these patterns are observed as a function of target atom number. The fragment pattern dependence on the target atom size is investigated within a simple model, normally used for stopping power calculations. Fair agreement is obtained between calculated and experimental spectra. From these comparisons we conclude that the range of the screened atomic potentials, as e.g., the Thomas-Fermi potential, is an essential parameter in the collisional induced fragmentation process.