Thermodynamic stability of diatomic dications of the families of alkaline earth oxides and hydrides: The cases of BaO2+ and BaH2+

Abstract

The low-lying electronic states of the diatomic dications BaO2+ and BaH2+ are investigated at a high level of theory. The potential energy curves constructed and the associated spectroscopic parameters provide a global and reliable characterization of these species attesting for their thermodynamic stability. The ground state (X 3Σ−) of BaO2+ is bound (De) by 13.11 kcal mol−1, with an equilibrium distance of 5.526 a0, and the harmonic constant (ωe) equal to 175.1 cm−1. The first excited state (A 3Π), lying higher by 3216 cm−1, is also thermodynamic stable (De = 4.04 kcal mol−1, ωe = 123.7 cm−1). Einstein spontaneous emission coefficients (Av′v″) were evaluated for all band systems, and lifetimes estimated. For the dication BaH2+, only the ground state (X 2Σ+) is thermodynamic stable with De = 5.50 kcal mol−1, Re = 5.444 a0, and ωe = 409.4 cm−1. New experimental results for the mass spectra of BaO2+ are also provided.