ROTATIONAL EFFECTS IN HD- THEORETICAL-STUDY OF RESONANT MECHANISMS AND COMPARISON WITH ION STORAGE-RING EXPERIMENTS( DISSOCIATIVE RECOMBINATION )

The cross section for dissociative recombination of HD+ ions is calcul ated in the energy range 1 meV-13 eV, using an extended MQDT approach which includes simultaneously electronic, vibrational and rotational i nteractions. We analyse the effect of rotation on the low-energy reson ance structure due to interfering bound Rydberg states, whereas at hig her energy, above the ion dissociation limit, competition with dissoci ative excitation is introduced. The absolute cross section measured in the ion storage ring CRYRING is well reproduced in shape and size bel ow 0.3 eV if the theoretical results are averaged with a 300 K Boltzma nn distribution of ion rotational levels, in equilibrium with the beam tube at room temperature. Beyond this energy and up to the ion dissoc iation threshold (2.7 eV), the experimentally measured cross section i s considerably larger than the theoretical one, although similarities in shape are still present. Above the dissociation limit, we obtain an overall good agreement between theory and experiment.