BOUND-BOUND AND BOUND-FREE FLUORESCENCE FROM THE $A^{1}{\Sigma^{+}}_{u}$ STATE TO THE $X^{1}{\Sigma^{+}}_{g}$ STATES IN $NA_{2}$

$^1$ W.T. Zemke, K.K. Verma, T. Vu and W.C. Stwalley, J. Mol. Spectrosc. 85, 150 (1981). $^2$ W. J. Stevens, M.M. Hessel, P.J. Bertoncini and A.C. Wahl, J. Chem. Phys. 66, 1477 (1977). $^3$ K.K. Verma, J. Bahns and W.C. Stwalley, J. Phys. Chem. 85, 2884 (1981).Using experimentally-based potential energy $curves^{1}$ and the theoretical transition $moment^{2}$, we report calculated bound-bound and bound-continuum radiative transition probabilities and calculated radiative lifetimes for several v', J', levels of the $A^{1}{\Sigma^{+}}_{u}$ state in $Na_{2}$. In the case of emission from the $A^{1}{\Sigma^{+}}_{u}$ (v' = 34, J' = 50) level, we present direct comparison with our recent laser-induced fluorescence $experiments^3$. Bound-bound Einstein A coefficients have been normalized to bound-free coefficients to show the continuity of the transition probability at the bound-continuum threshold. We demonstrate how the spectrum in the threshold vicinity provides a means to improve the value of the $X^{1}{\Sigma^{+}}_{g}$ ground state dissociation energy