Abstract
A merged-beams technique is used to measure charge transfer (CT) cross sections for the (O2+,D) and (CO+,D) systems from 2 keV/u to 20 eV/u, which covers a wide range of energy: high energies where the collision is ro-vibrationally frozen to low energies where ro-vibrational modes become important. At high energies where the differences in the Q-values of the CT process can be neglected, the cross sections all converge to (7.5 ± 0.5) x 10-16 cm2 at 2 keV/u and are consistent with a H2+ + H calculation which assumes the ro-vibrational modes are frozen. Toward lower velocities, (O2+,D) and (CO+,D) have consistently similar cross sections, as one might expect from the comparison of their characteristic vibrational time, but diverge below 60eV/u. In contrast, previously reported merged-beams measurements for (D2+,H), a system with fewer electrons on the molecular core, no electronic excited states and with relatively less charge transfer channels, shows a decreasing cross section toward lower energies. These different trends are compared to merged-beams measurements of charge transfer for several 4+ atomic ions that have a different number of electrons on the core.
