Collisional Electron Detachment from 20-MeVD0andD−Ions

Cross sections for collisional electron detachment from 20-MeV deuterium atoms and negative ions have been measured in ${\mathrm{H}}_2$, He, ${\mathrm{N}}_2$, and Ar. The cross sections ${\sigma }_{01}$ per target molecule for the ionization of neutral atoms are 2.2, 1.6, 20, and 36, respectively, in units of ${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$. Results for single-electron detachment from ${\mathrm{D}}^{-}$ ions, ${\sigma }_{-10\mathrm{}}$, are 7.5, 4.7, 58, and 75, respectively. All values have an uncertainty of ±10%, chiefly from absolute-pressure calibration uncertainties. The experimental values for atoms in ${\mathrm{H}}_2$ and He are in agreement with calculations that use the Born and free-collision approximations. The measured cross sections for single-electron detachment from negative ions in ${\mathrm{H}}_2$ and He are about one-half of the calculated values. The two-electron detachment cross sections, ${\sigma }_{-11\mathrm{}}$, are approximately 4% of the single-detachment cross sections, ${\sigma }_{-10\mathrm{}}$, in all gases.