Dissociation Energy of the Ground State of NaH

The dissociation energy of the ground state of NaH has been determined by analyzing the observed near dissociation rovibrational levels of X$^1\Sigma^+$ and C$^1\Sigma^+$ states. These levels are carried out by stimulated emission pumping and fluorescence depletion spectroscopy. The highest vibrational level observed in ground state is only about 40\,cm$^{-1}$ from its dissociation limit and is about 30\,cm$^{-1}$ from its dissociation limit for C$^1\Sigma^+$ state. Determining the vibrational quantum number at dissociation $v_D$ from the highest four vibrational levels of ground state yields the dissociation energy $D_e$=15\,815$\,\pm\,$5\,cm$^{-1}$. A Hybrid potential based on the rotationless Rydberg-Klein-Rees curve and the modified \emph{ab} initio calculation is constructed for the C$^1\Sigma^+$ state. The dissociation energy of ground state can be deduced from the asymptotic limit of C$^1\Sigma^+$ state and it agrees well with obtained from the ground state $v_D$.