Abstract
Using ab initio methodology, we studied the IOq+ (q = 2, 3, 4) multi-charged ions. Benchmark computations on the IO(X-2 Pi) neutral species allow validate the current procedure. For IO2+, several potential wells were found on the ground and the electronic excited states potentials with potential barriers with respect to dissociation, where this dication can exist in the gas phase as long-lived metastable molecules. We confirm hence the recent observation of the dication by mass spectrometry. Moreover, we predict the existence of the metastable IO3+ trication, where a shallow potential well along the IO internuclear distance is computed. This potential well supports more than 10 vibrational levels. The IO3+ excited states are repulsive in nature, as well as the computed potentials for the IO4+ tetracation. For the bound states, we give a set of spectroscopic parameters including excitation transition energies, equilibrium distances, harmonic and anharmonic vibrational terms, and rotational constants. At the MRCI + Q/ aug-cc-pV5Z(-PP) level, the adiabatic double and triple ionization energies of IO are computed to be similar to 28.1 eV and similar to 55.0 eV, respectively. (C) 2014 AIP Publishing LLC.