Spectroscopic determination of the ground-state dissociation energy and isotopic shift of NaD.

Stimulated emission pumping with fluorescence depletion spectroscopy is used to determine the NaD X Σ ground-state dissociation energy and its isotopic shift. A total of 230 rovibrational levels in the range 9 ≤ v″ ≤ 29 and 1 ≤ J″ ≤ 11 are observed, where v″ = 29 is about 50 cm below the dissociation limit. Analysis of the highest five vibrational levels yields the dissociation energy D = 15 822 ± 5 cm with a vibrational quantum number at dissociation v = 31.2 ± 0.1. The energy difference in the well depth of this isotopologue with respect to that of NaH is δD = D(NaH) - D(NaD) = -7 cm. A new set of Dunham coefficients is derived to fit all the observed energy levels to within the experimental uncertainty.