Experimental studies of metastable and dissociative states of doubly-charged molecular ions

High resolution ion translational energy loss spectrometry has been applied to study products of electron-loss collisions and double electron capture collisions leading to formation of doubly charged molecular ions. A case study is reported on the lowest-energy metastable and unstable electronic states of CO2+ ions. Our experimental data is utilised to assess the reliability of recent calculations of CO2+ potential energy curves using relatively straightforward SCF techniques, such as MNDO, as well as a number of high-level ab initio molecular orbital methods