Resonant ion-pair formation in electron collisions withHD+andOH+

Resonant ion-pair formation from collisions of electrons with electronic and vibronic ground-state diatomic molecular ions has been studied in the present work for ${\mathrm{HD}}^{+}$ and ${\mathrm{OH}}^{+}.$ The cross section for ${\mathrm{HD}}^{+}$ has a magnitude of the order of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19} {\mathrm{cm}}^{2}$ and is characterized by an energy threshold and 14 resolved peaks in the energy range up to 16 eV. A theoretical study confirms that the structures derive primarily from quantum interference of the multiple dissociation pathways. Measurements for ${\mathrm{OH}}^{+}$ reveal that the cross section for ${\mathrm{H}}^{+}$ and ${\mathrm{O}}^{\ensuremath{-}}$ formation is lower than ${10}^{\ensuremath{-}21} {\mathrm{cm}}^{2}$ at energies of 6 and 12 eV.