THE $A^{1} \Sigma^{+}_{u} \leftarrow X^{1} \Sigma_{g}$ SPECTRUM OF $Li_{2}$ REVISITED

Abstract

Our previous theoretical calculation of the A $\leftarrow$ X $Spectrum^{1}$ is reexamined in light of the new analysis of the spectrum by Kusch and Hessel (KH)$^{2}$. We corroborate the KH assignment of Dunham constants $Y_{i, 0}$ for the A state by comparison with vibrational energy eigenvalues based on our accurate multiconfiguration self-consistent field (MCSCF) calculations. The MCSCF potential suggests that dissociation of $A^{1}\Sigma_{u}^{+}$ occurs at $v^{\prime} \cong 103$ at an energy $D_{e} = 9299$ $cm^{-1}$. A semiempirical scaling of this result gives our best estimate of $D_{e} = 9400$ $cm^{-1}$. A wager offered last year regarding the A state potential will be repeated and an even more generous one will be offered this year.