Observation of new ring isomers for carbon cluster anions

High-resolution ion-mobility measurements have resolved a number of isomers for carbon cluster anions in the drift-time region previously assigned to monocyclic rings. Tight-binding calculations have been performed to generate feasible geometries, which were compared to the experimental data by calculating their mobilities. Structures composed of a short chain of carbon atoms attached to a carbon ring are found to be the most plausible geometries for these new isomers. A number of different bicyclic ring isomers have also been resolved for the first time.