Measured appearance energies of C-n(+) (3<=n<=10) fragment ions produced by electron impact on C-60

We have used mass spectrometric techniques to determine the appearance energies for the formation of small, singly charged C-n(+) fragment ions (3 less than or equal to n less than or equal to 10) produced by controlled electron impact on C-60 under single collision conditions. The measured appearance energies range from 79 eV (C-3(+)) to 91 eV (C-10(+)) and show, within the experimental error bar of +/-5 eV, little variation with the cluster size. This result is distinctly different from the behaviour of the previously measured appearance energies for the large fragment ions C-58(+) to C-44(+) and indicates that the small fragment ions are the result of a different fragmentation pathway.