Abstract

The C-state of CO⁺ has been studied using UV photoelectron spectroscopy. The spectrum was excited by a monochromatized HeIIa, ECR source. The vibrational progression in the C slate has earlier been observed up to ?=6 and an anomalous anharmonicity has been inferred. In the present spectrum the progression has been followed up to v=11 and the progression can be described as originating from two nearly harmonic potentials. A perturbation is thus found for the C state at an internuclear distance of about 1.4 Å. Moreover, the progression extends 0.2 eV above the dissociation limit and therefore a potential barrier must exist with a maximum around 2.3 Å.