Investigation of Charge Transfer in Low Energy $D_2^+$ + H Collisions using Merged Beams*

The hydrogen - hydrogen(deuterium) molecular ion is the most fundamental ion-molecule two-electron system. Charge transfer proceeds through dynamically coupled electronic, vibrational and rotational degress of freedom. Using the ion-atom merged- beams apparatus at Oak Ridge National Lab we have measured absolute charge transfer cross sections for D$_2^+$ + H from keV/u collision energies where the collision is considered ``ro-vibrationally frozen'' to meV/u energies where collision times are long enough to sample vibrational and rotational modes. The molecular ions are extracted from an ECR ion source with a distribution of ro-vibrational states. The measurments benchmark high energy theory (Errea et al., NIMB 235, 362 (2005) and vibrationally specific adiabatic theory (Krstic PRA 66, 042717 (2002)).