Resonance structure in the electron-impact detachment cross section of C-2(-) caused by the formation of C-2(2-)

Electrons have been scattered on C-2(-) in the energy range from 0-35 eV. A resonance structure in the e(-) + C-2(-) --> C-2 + 2(e)(-) detachment channel was observed at an energy of about 10 eV. To explain the structure, a C-2(2-) potential curve was constructed from the isoelectronic N-2 ground-state potential curve and the repulsive Coulomb potential, and it is argued that the structure may be related to the population of a C-2(2-) state. The state is predicted to decay primarily by electron emission since a large potential barrier prevents dissociation into C- + C-.