The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9 <= v ''<= 21 and 1 <= J ''<= 14 were assigned to the X (1)Sigma(+) state of NaH. The highest vibrational level observed was only about 40 cm(-1) from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation up from the highest four vibrational levels yielded the dissociation energy D-e=15 815 +/- 5 cm(-1). Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3458914]

The outer well of the NaH C1Σ+ excited state was determined using pulsed optical–optical double resonance fluorescence depletion spectroscopy. The level-selected fluorescence of the A1Σ+ state is depleted back to the ground state when a probe laser excites the molecules to the C1Σ+ state. A total of 456 rovibrational levels, v=5–33 and J=1–11, were observed. A set of Dunham constants and the Rydberg–Klein–Rees (RKR) potential curve for the outer well were reported.