Novel decay channels of carbon cluster ions, C40z+ and C41z+ (z=3,4)

We have analyzed spontaneous decay reactions of triply and quadruply charged C40z+ and C41z+ cluster ions which are formed from C60 fullerenes by electron-impact ionization. A new but very weak decay reaction for the even-sized carbon cluster ions is observed, namely loss of C3. The odd-sized cluster ions preferentially decay by loss of carbon atoms and, to a lesser degree, trimers. A weak signal due to C2 loss is observed for C413+. We discuss these decay channels in terms of the geometric structure of these metastable, relatively cold cluster ions.