UNIMOLECULAR DISSOCIATION OF SINGLY-CHARGED AND MULTIPLY-CHARGED FULLERENE IONS

The formation of fragment ions from C-60 due to electron impact ioniza tion leading to a bimodal fragmentation pattern with a minimum around the cluster size of 30 is investigated with help of mass spectrometric techniques. Based on a detailed analysis of the energetics and kineti cs of the singly- and multiply-charged fragment ions by two-sector fie ld mass spectrometry (MIKE-scans) we can conclude that on the one hand some of the dissociation reactions proceed via evaporation of an inta ct C-6(+) or C-4(+) unit (and not via the sequential loss of smaller m olecular carbon units). On the other hand, measured appearance energie s and the direct observation of sequential C-2-loss reactions confirm that the sequential loss of neutral C-2 units is the dominant producti on mechanism for C-n(z+) fragment ions with sizes 40 < n < 60.