Charge Transfer in Collisions between Molecular Ions and Atomic Hydrogen/Deuterium$^{1}$

Using the Oak Ridge National Laboratory ion--atom merged--beams apparatus, absolute cross sections of direct and dissociative charge transfer (CT) between H/D and different molecular ions (D$_{2}^{+}$, CO$^{+}$, and O$_{2}^{+})$ are measured from 20 eV/u to 2 keV/u collision energies. Toward high energy where the differences in Q-value of the reaction can be neglected and the rovibrational modes can be considered as frozen, the measured cross sections for the diatomic ions all converge to (7 $\pm $ 0.5) x 10$^{-16}$ cm$^{2}$ at 2 keV/u and are consistent with a rovibrational frozen (H$_{2}^{+}$, H) calculation (Physical Review A 84, 062716, 2011). Below one keV/u collision energy, the measured cross sections exhibit trends which are compared to previous merged-beams measurements of CT with H for atomic ions with a variety of electrons on the core. \\[4pt] $^{1}$Research supported by the NASA Solar {\&} Heliospheric Physics Program NNH07ZDA001N, the Office of Fusion Energy Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy, the National Science Foundation through Grant No. PHY-106887.