Dissociative recombination of electrons andD2+to yieldD(2p)

Cross sections have been measured as a function of electron energy (1.4 to 7.5 eV) for production of $L_{\alpha }$ photons from the dissociative recombination of electrons and ${\mathrm{D}}_2^{+}$. Ions made in a low-pressure ion source by electron bombardment and formed into a beam are reacted at right angles with a magnetically confined electron beam. Recombination was observed by detecting $L_{\alpha }$ photons from resultant excited atoms. It was demonstrated that a large fraction of the observed light arises from cascade to the $2p$ state from levels of higher principal quantum number. The measured cross section is thus presented as an upper limit for formation of $\mathrm{D}\mathrm{}\left(2p\right)\mathrm{}$ in the dissociative recombination process. The results, represented approximately by the expression $\sigma \mathrm{}\left(2p\right)<(7.6\mathrm{}\times {10}^{-17\mathrm{}})E^{-1.25\mathrm{}}$ ${\mathrm{cm}}^2$, indicate that recombinations leading to formation of a $\mathrm{D}\mathrm{}\left(2p\right)\mathrm{}$ are a small fraction of the total recombination measured by Peart and Dolder.