Long-lived, doubly charged diatomic and triatomic molecular ions

This is the authors' abstract. We don't add key points for this paper.

Lifetimes of doubly charged diatomic and triatomic molecules have been measured by monitoring the decay curves of such ions in a heavy-ion storage ring. CO 2+ , N 2 2+ , CO 2 2+ , CS 2 2+ and SH 2+ are all found to possess long-lived components which survive for time periods greater than a few seconds. All these dications are found to be essentially stable and their ultimate destruction is due to interactions with residual gases in the ring. CO 2+ possesses many more lifetime components in the millisecond range than the isoelectronic N 2 2+ ion. Translational energy spectrometry experiments on the latter species also fail to reveal any short-lived (microsecond) components. Ab initio configuration interaction calculations have been carried out and the potential energy curve for the lowest-energy metastable state of N 2 2+ ( 1 Sigma g ) has been determined, along with Franck-Condon factors for vertical transitions to different vibrational levels from the ground state of neutral N 2 ; tunnelling times of each vibrational level have been computed.