Charge Transfer inNa+-O−Collisions at Low Relative Energy

Abstract

Total cross sections have been measured for electron transfer from ${\mathrm{O}}^{-}$ to ${\mathrm{Na}}^{+}$, resulting in optically allowed transitions to $\mathrm{Na}\left({}_{}{}^2{}_{}{}^{}S\right)$ ground state. A merged-beam technique was used to study the collisions in the energy range 0.1-7 eV. Structure in the curves of cross sections vs relative energy indicates that the excitation of oxygen plays an important role in the charge-transfer process. Cross sections for an endoergic process, giving $\mathrm{Na}\mathrm{}\left(4p\right)\mathrm{}$, are of order ${10}^{-14\mathrm{}}$ ${\mathrm{cm}}^2$; cross sections for the exoergic processes leading to production of $\mathrm{Na}\mathrm{}\left(3d\right)\mathrm{}$ and $\mathrm{Na}\mathrm{}\left(3p\right)\mathrm{}$ are of order ${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$. Production of $\mathrm{Na}\mathrm{}\left(3d\right)\mathrm{}$ is nearly a resonant process; production of $\mathrm{Na}\mathrm{}\left(3p\right)\mathrm{}$ is apparently due to a cascade from $\mathrm{Na}\mathrm{}\left(3d\right)\mathrm{}$.