Three structural types of carbon cluster anions and the magic numbers

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Abstract
The distribution of negative carbon clusters, C, is studied in the size range from 4 to 100 atoms using a Smalley compact supersonic source interfaced to a Fourier transform mass spectrometer. Tht mass spectrum of the anion clusters shows three regions which, based on earlier work, can be assigned to three different types of structures: chain, monocyclic and fullerene. The boundaries observed for the three regions in the mass spectrum suggest that the transition from chain to cyclic structure occurs between C and C, and the one from cyclic structure to fullerene occurs in the region of C to C. Magic numbers in the cyclic cluster region are found to be 17, 21, 25, 29 and 33 (n = 4m + l), and in the fullerene region, 60 and 74. Water can react with carbon clusters in the supersonic source to form hydrogenation products followed by electron attachment to give CnH− and CnH (for even n smaller than about 22). With argon as the target gas, only small C (n < 14, except n = 4) are observed to undergo low energy collision‐induced dissociation (CID) yielding mainly C. While CID of CnH− gives C, no product was observed during CID of CnH.