Knowledge Bank

Lasing has been observed on a nearly atomic O($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$S)-O($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$D) transition (5577 \AA) in argon-, krypton-, and xenon-oxygen mixtures and it has been attributed to a weakly bound rare gas monoxide. We report a brief summary of ab initio configuration Interaction calculations on all of the electronic states of RgO (Rg = Ne, Ar, Kr, and Xe) arising from the $Rg(1S)+O(3P,1D,and1S)$ limits. All states, with the exception of the $11\Sigma +$ state, are found to be unbound (with at most van der Waals’ minima). The binding in the $11\Sigma +$ state is due in large part to the incorporation of $Rg+(2P)+0-(2P)$ character and increases in the series: Ne(unbound) to Ar(essentially flat) to Kr(bound) to Xe(bound). The admixture of ionic character in the $11\Sigma +$ state also strongly enhances the $21\Sigma +-11\Sigma +$ transition.