Analysis of the polarization-dependent rate of associative ionization of radiatively excited Na(3p) atoms

Kircz, Morgenstern, and Nienhuis [Phys. Rev. Lett. 48, 610 (1982)] have measured the cross section for the associative ionization of partially oriented pairs of excited [(3p) ${}_{}{}^2{}_{}{}^{}P_{3/2}^{}{}_{}{}^{}$] sodium atoms. Here, we extract information from these data about the identities of the participating adiabatic Born-Oppenheimer states of ${\mathrm{Na}}_2$. It is definitely established that more than one of these states is involved. The greatest contributor is the X ${}_{}{}^1{}_{}{}^{}\Sigma _g^{+}{}_{}{}^{}$ state with the dominant molecular-orbital configuration ${\sigma }_g^2$ (at small internuclear separations). It is highly probable that only one other state (either the ${}_{}{}^1{}_{}{}^{}\mathrm{\Sigma }_{\mathrm{g}}^{+}{}_{}{}^{}$ or ${}_{}{}^3{}_{}{}^{}\mathrm{\Sigma }_{\mathrm{g}}^{\mathrm{-}}{}_{}{}^{}$ state with the dominant molecular-orbital configuration ${\pi }_u^2$) is involved, but a small contribution from one state ${(}^1$ ${\Pi }_u$ or ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{}{}_{}{}^{}$) with the configuration ${\sigma }_g$ ${\pi }_u$ cannot be unequivocally dismissed.