| 1. |
- Larson, Åsa, et al.
(författare)
-
Theoretical study of mutual neutralization in He+ + H- collisions
- 2016
-
Ingår i: Physical Review A. - 2469-9926. ; 94:2
-
Tidskriftsartikel (refereegranskat)abstract
- Total and differential cross sections for mutual neutralization in He+ and H- collisions at low to intermediate (0.001 eV to 100 eV) are calculated ab initio and fully quantum mechanically. Atomic final-state distributions and isotope effects are investigated. The theoretical model includes dynamics on eleven coupled states of (2)Sigma(+) symmetry, where autoionization is incorporated. The potential-energy curves, autoionization widths, and nonadiabatic couplings of electronic resonant states of HeH are computed by combining structure calculations with electron scattering calculations. The nuclear dynamics is studied using a strict diabatic representation of the resonant states. Effects of rotational couplings between (2)Sigma(+) and (2)Pi electronic states are investigated in the pure precession approximation.
|
|
| 2. |
- Nkambule, Sifiso M., et al.
(författare)
-
Differential and total cross sections of mutual neutralization in low-energy collisions of isotopes of H+ + H-
- 2016
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 93:3
-
Tidskriftsartikel (refereegranskat)abstract
- Mutual neutralization in the collisions of H+ and H- is studied both theoretically and experimentally. The quantum-mechanical ab initio model includes covalent states associated with the H(1)+H(n <= 3) limits and the collision energy ranges from 1 meV to 100 eV. The reaction is theoretically studied for collisions between different isotopes of the hydrogen ions. From the partial wave scattering amplitude, the differential and total cross sections are computed. The differential cross section is analyzed in terms of forward- and backward-scattering events, showing a dominance of backward scattering which can be understood by examining the phase of the scattering amplitudes for the gerade and ungerade set of states. The isotope dependence of the total cross section is compared with the one obtained using a semiclassical multistate Landau-Zener model. The final state distribution analysis emphasizes the dominance of the n = 3 channel for collisions below 10 eV, while at higher collision energies, the n = 2 channel starts to become important. For collisions of ions forming a molecular system with a larger reduced mass, the n = 2 channel starts to dominate at lower energies. Using a merged ion-beam apparatus, the branching ratios for mutual neutralization in H+ and H- collisions in the energy range from 11 to 185 eV are measured with position- and time-sensitive particle detectors. The measured and calculated branching ratios satisfactorily agree with respect to state contributions.
|
|
| 3. |
- Nkambule, Sifiso M., et al.
(författare)
-
Mutual neutralization in collisions of Li+ and F-
- 2015
-
Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104 .- 1873-4421. ; 462, s. 23-27
-
Tidskriftsartikel (refereegranskat)abstract
- Mutual neutralization in collisions of Li+ and F is driven by an avoided crossing between the two lowest (1)Sigma(+) electronic states of the LiF system. These electronic states are computed using the multi-reference configuration interaction method. We investigate how the adiabatic potential energy curves and the non-adiabatic coupling element depend on the choice of the reference configurations as well as the basis set. Using diabatic states, the total and differential cross sections for mutual neutralization are computed.
|
|
| 4. |
- Nkambule, Sifiso M., et al.
(författare)
-
Theoretical study of the mechanism of H2O+ dissociative recombination
- 2015
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 92:1
-
Tidskriftsartikel (refereegranskat)abstract
- By combining electronic structure and scattering calculations, quasidiabatic potential energy surfaces of both bound Rydberg and electronic resonant states of the water molecule are calculated at the multireference configuration-interaction level. The scattering matrix calculated at low collision energy is used to obtain explicitly all couplings elements responsible for the electronic capture to bound Rydberg states. These are used to estimate the cross section arising from the indirect mechanism of dissociative recombination. Additionally, the role of the direct capture and dissociation through the resonant states is explored using wave-packet propagation along one-dimensional slices of the multidimensional potential energy surfaces.
|
|
