The absolute dissociative recombination and absolute dissociative excitation rate coefficients and cross sections have been determined for N2+ and electrons for collision energies between 10 meV and 30 eV. The ion storage ring CRYRING has been used in combination with an imaging technique with a position-and-time-sensitive detector. Information is retrieved on the ion beam vibrational state populations and on the product branching in the dissociative recombination process at 0 eV collisions. A hollow cathode ion source has been used to lower the vibrational excitation in the ion beam; a more traditional hot-cathode ion source was used as well. The most important findings are the following. The rate coefficient for an N2+ ion beam (46%, v=0, 27% v=1) versus electron temperature (K) is α(Te)=1.75(±0.09)×10−7(Te/300)−0.30 cm3 s−1. The dissociative recombination rate is found to be weakly dependent on the N2+ vibrational level. At 0 eV collision energy, the v=0 product branching is found to be 0.37(8):0.11(6):0.52(4) for N(4S)+N(2D):N(2P)+N(4S):N(2D)+N(2D) fragments. The dissociative recombination cross section does not have a high-energy peak as was found in a number of lighter molecular systems. The dissociative excitation signal starts only slightly above the energy threshold for dissociation, and peaks near 25 eV. From the dissociative excitation data and literature data, information is retrieved on the dissociative ionization of N2+. The comparison of these results with earlier DR measurements is extensively discussed.

No abstract

No abstract

The cross section for dissociative recombination of HD + ions is calculated in the energy range 1 meV-13 eV, using an extended MQDT approach which includes simultaneously electronic, vibrational and rotational interactions. We analyse the effect of rotation on the lowenergy resonance structure due to interfering bound Rydberg states, whereas at higher energy, above the ion dissociation limit, competition with dissociative excitation is introduced. The absolute cross section measured in the ion storage ring CRYRING is well reproduced in shape and size below 0.3 eV if the theoretical results are averaged with a 300 K Boltzmann distribution of ion rotational levels, in equilibrium with the beam tube at room temperature. Beyond this energy and up to the ion dissociation threshold (2.7 eV), the experimentally measured cross section is 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.

No abstract