PRODUCTION, DISSOCIATION AND REACTIVITY OF CARBON CLUSTER ANIONS

Negative carbon cluster ions, C(n)- (n less-than-or-equal-to 13), produced by the direct laser vaporization of graphite have been studied by using Fourier transform mass spectrometry. Low-energy collision-induced dissociation (CID) of C(n)- (n = 5-13) results in loss of neutral C3 which also competes with electron detachment. The ion/molecule reactions of C(n)- (n = 4-13) with F2 and C2N2 indicate that only linear C(n)- are formed by direct laser vaporization. No evidence for structural isomers of C(n)- is observed, although product ion isomers are formed in the reaction of C5- with C2N2. The C5C2N2- isomers are differentiated by differences in their reactivity and CID spectra. The differences observed in the reactivity and CID of reaction products for odd and even n are consistent with polyacetylene (even n) and cumulene (odd n) structures for the carbon clusters. These results are compared with previous C(n)- studies, including a discussion of structural implications and formation mechanisms of C(n)- produced by various techniques.