The CH²⁺ dication: Metastable or not? A combined theoretical and experimental investigation

New charge-stripping mass spectrometry experiments give no indication of metastable CH2+ dications, contrary to earlier experiments. This result is supported by extensive ab initio calculations using a large Slater-type basis set on the three lowest 2Σ+ states of CH2+. Although the ground state potential curve is considerably perturbed by excited states, the perturbations are not sufficient to generate a potential minimum. The experimental artifacts encountered in the previous experimental studies which led to the erroneous conclusion of CH2+ as a metastable dication are analyzed. © 1987.