Isomers of Small Carbon Cluster Anions: Linear Chains with up to 20 Atoms

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Science  26 Feb 1993:
Vol. 259, Issue 5099, pp. 1300-1302
DOI: 10.1126/science.259.5099.1300


The structure of small carbon cluster anions, Cn- (4 ≤ n ≤ 20), was investigated with the use of ion chromatography. With this technique, both the existence and the relative amounts of possible structural isomers can be determined. More than 99% of the ions C5- to C9- were found to be linear under these experimental conditions. Starting with C10-, a monocyclic isomer was observed, and linear and moncyclic structures coexisted from C10- through at least C20-. This result is in contrast to previous work on positive ions, which showed the existence of linear isomers from C5+ to C10+, with linear and cyclic isomers coexisting only from C7+ to C10+. Above C10+, no linear clusters were observed.