Low-lying electronic states of the rare gas oxides

A b initio configuration interaction calculations have been carried out on the electronic states of RgO (Rg=Ne, Ar, Kr, and Xe) arising from the Rg(1S)+O(3P, 1D, and 1S) separated atom limits. All potential curves, with the exception of the 1 1Σ+ curve in KrO and XeO, are found to be repulsive (with at most van der Waals minima). The binding in the 1 1Σ+ state is due in part to the incorporation of Rg++O− character and increase in the series: NeO (unbound) to ArO (essentially flat) to KrO (De=0.25 eV) to XeO (De=0.70 eV). The admixture of ionic character into the 1 1Σ+ state also strongly enhances the 2 1Σ+–1 1Σ+ transition, increasing the collision induced emission rate from O(1S) and decreasing the lifetime of the 2 1Σ+ state. The calculations also provide information on the quenching of O(1D) by the rare gases.