Formation of doubly charged Co²⁺ ions: a combined experimental and theoretical study

Abstract

The formation of doubly charged molecular ions of carbon monoxide is studied by means of ion translational energy spectrometry of products resulting from electron loss collisions of CO⁺ and He and double electron capture collisions of H⁺ and CO. Theoretical calculations of potential energy functions of several low-lying states of CO²⁺ have been carried out using a high level, all-electron ab initio technique using large Gaussian basis sets. Vertical double ionisation energies of CO are measured to be 40.21+or-0.35 eV and 39.45+or-0.20 eV. The former value pertains to a metastable CO²⁺ state whereas the latter is ascribed to a dissociative state. The energy difference of 0.76 eV is a measure of the splitting between the lowest ³ Pi and ¹ Pi states.