1. Ion-Atom Collisions Electron capture reactions in N2+, O2+ + H
Ion-Atom Collisions Electron capture reactions in N2+, O2+ + H
Patricia Barragán
Laboratorio asociado al CIEMAT de Física Atómica y Molecular en Plasmas de Fusión
Departamento de Química, Universidad Autónoma de Madrid
September 28, 2005

2. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Motivation
Fusion plasmas.
Plasma-wall interaction Impurities.
Plasma diagnostics (CXS).
Astrophysics.
Comets X-ray emission .
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

3. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
N2++ H and O2++ H collisions.
Presence of metastable ions in beams.
Calculation of rate coefficients.
Computational characteristics:
Many electron systems. Use of Quantum Chemistry techniques.
Calculation in a wide energy range: Quantal and semiclassical treatments.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

4. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
N2+ + H collisions
Reaction (1)
Reaction (2)
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

5. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
O2+ + H collisions
Reaction (3)
Reaction (4)
Reaction (5)
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

6. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Quantal treatment
Schrödinger equation
Boundary conditions (one electron systems)
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

7. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Molecular expansion
k are eigenfunctions of Helec
 is the Common Reaction Coordinate, which ensures that a
truncated expansion satisfies the scattering boundary conditions:
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

8. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Cross Sections
are solutions of the system of differential equations:
The total Cross Section for transition i→j is given by:
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

9. Semiclassical treatment
The nuclei follow straight-line trajectories:
The electronic motion is described by the eikonal equation:
Molecular close-coupling treatment:
where D(r,t) is a common translation factor.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

10. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Cross Sections
where the probability Pij for transition to the final state is
calculated from the coefficient aj(t):
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

11. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Computational scheme
Calculation of electronic energies:MRCI (MELDF)
- GTO bases (Widmark et al. Theor.Chim. Acta. 77, 291 (1990))
- 80 reference configurations, iterative process to select the set of reference configurations at each R.
- Frozen core approximation.
- Perturbative selection.
Calculation of dynamical couplings.
- Numerical differentation (Castillo et al. J Chem. Phys. 03,2113(1995))
- Sign consistency: calculation of the delayed overlap matrix (Errea et al. J Chem. Phys. 121,1663 (2004))
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

12. N2+ + H Potential energy curves: singlets
c.e.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

13. N2+ + H Potential energy curves: triplets
c.e.
c.e.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

14. N2+ + H Potential energy curves: triplets
c.e.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

15. N2+ + H Potential energy curves: triplets
c.e.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

16. N2+ + H Potential energy curves: quintets
c.e.
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

17. N2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

18. N2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

19. N2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

20. N2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

21. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
N2+ + H Branching ratios
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

22. O2+ + H Potential energy curves: doublets
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

23. O2+ + H Potential energy curves: cuadruplets
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

24. O2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

25. O2+ + H Total cross sections
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

26. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
O2+ + H Branching ratios
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

27. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Rate coefficients
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

28. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Rate coefficients
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

29. Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H
Concluding remarks
N2+ + H, O2+ + H collisions.
Quantal calculation for low energy and semiclassical for high energy.
Presence of metastable ions in beams: Possible presence of N2+(2s2p2 4P) in merged beams experiments. Not noted in other experiments.
Very large cross sections at low energies - shape resonances?
Calculation of partial EC cross sections (diagnostics).
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

30. Thanks to… L. Méndez, I. Rabadán, L. F. Errea and A. Riera
who have participated directly in this work.
And the other group members:
L. Fernández, F. Guzmán, C. Illescas, A. Macías
and J. Suarez
Group web-site:
Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H