A spectroscopic determination of the bond length of the LiOLi molecule: Strong ionic bonding

The short bond length of the linear ground state of the 7Li16O7Li molecule has been accurately determined to be 1.606±0.008 Å by analysis of the rotational structure of several bands assigned to transitions from the jet-cooled 1Σ+ vibronic ground state to a bent 1B1 excited state. This value is in good agreement with, but more accurate than, other experimental and ab initio bond-length estimates for the prototypical ionically bound triatomic molecule Li+O−2Li+.