We report experimental and theoretical results for associative detachment (AD) of ${\mathrm{D}}^{-}+\mathrm{D}\to {\mathrm{D}}_2+e^{-}$. We compare these data to our previously published results for ${\mathrm{H}}^{-}+\mathrm{H}\to {\mathrm{H}}_2+e^{-}$. The measurements show no significant isotope effect in the total cross section. This is to be contrasted with previously published experimental and theoretical work which has found a significant isotope effect in diatomic systems for partial AD cross sections, i.e., as a function of the rotational and vibrational levels of the final molecule formed. Our work implies that though the rovibrational distribution of flux is different for AD of H${}^{-}$ $+$ H and D${}^{-}$ $+$ D, the total flux for these two systems is essentially the same when summed over all possible final channels.

• Received 1 March 2012

DOI:https://doi.org/10.1103/PhysRevA.86.032714