Light-ionic fragment production in dissociative electron–molecular-ion collisions: Detection ofD+andD2+fromNDn+(n=2–4)andODn+(n=2,3)

Abstract

Absolute cross sections are reported for the electron impact dissociative excitation of the deuterated ions ${\mathrm{ND}}_{n}^{+}$ $(n=2\ensuremath{-}4)$ and ${\mathrm{OD}}_{n}^{+}$ $(n=2,3)$ from threshold up to 70 eV using a crossed beams technique. The method focuses on measuring light dissociation-product ions from a heavy target. For all studied targets, ${\mathrm{D}}^{+}$ formation is the dominant channel, with absolute cross section values in the range of $(1.3\ensuremath{-}2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{2},$ once the initial rise from the threshold is past, continuing to 70 eV. The present measurements for dissociation of ${\mathrm{OD}}_{2}^{+}$ and ${\mathrm{OD}}_{3}^{+}$ yielding ${\mathrm{D}}^{+}$ are compared with recent results obtained in the storage ring experiments, these cross sections are found to be in a reasonable agreement within the quoted uncertainties over the part of the energy range where they are expected to be the same. The cross sections for obtaining ${\mathrm{D}}_{2}^{+}$ are about an order of magnitude smaller than the cross sections for ${\mathrm{D}}^{+}$ formation from the same targets.