Global analysis of the NaNe excimer band systems: A molecule between Hund’s cases

We have least-squares fit 244 transitions in the mutually perturbing NaNe A 2Π–X 2Σ+ and B 2Σ+–X 2Σ+ excimer band systems using a Hund’s case ’’c’’ basis. Interatomic potentials were determined by matching computed spectroscopic parameters to 43 fitted parameters. This deperturbation analysis implies that the Na atomic angular momentum qunatum numbers—L and S—are also good molecular quantum numbers. NaNe exhibits an intramolecular transition from Hund’s case c to Hund’s case ’’a’’ angular momentum coupling as the internuclear distance is decreased. The nature of this transition is mediated by the shapes, depths, and positions of both the A 2Π and B 2Σ+ van der Waals potentials.