A molecular approach employing quantum close-coupling calculations has been utilized to calculate the cross sections for the reactions $\mathrm{Na}\left(n{}_{}{}^2{}_{}{}^{}D\right)+\mathrm{H}\mathrm{e},\mathrm{N}\mathrm{e},\mathrm{A}\mathrm{r}\to \mathrm{Na}\left(n{}_{}{}^2{}_{}{}^{}F\right)+\mathrm{H}\mathrm{e},\mathrm{N}\mathrm{e},\mathrm{A}\mathrm{r}$ for $4\le n\le 20$ at a collision energy of 0.04 eV. The calculations employ exact asymptotic coupling matrix elements and the recently measured term splittings for the $\mathrm{Na}(n{}_{}{}^2{}_{}{}^{}D-n{}_{}{}^2{}_{}{}^{}F)$ sequence. The cross sections are found to rise rapidly with increasing $n$ to a maximum cross section of the order ${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$ at $n$ values of 7-12. For larger values of $n$, the cross sections decrease with increasing $n$. The magnitude of the maximum cross section is found to roughly correlate to the electron scattering length of the noble-gas perturbing atom. The theoretical calculations compare well with recent experimental measurements of Gallagher, Edelstein, and Hill.

• Received 7 July 1976

DOI:https://doi.org/10.1103/PhysRevA.15.631