Ion-Atom Collisions Electron capture reactions in N 2+ , O 2+ + H

1. patricia.barragan@uam.es barragan@phys.ksu.edu Ion-Atom CollisionsElectron 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. 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. 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. N2+ + H collisions Reaction (1) Reaction (2) Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

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

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

7. Molecular expansion kare 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. 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. 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. 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. c.e. c.e. N2+ + H Potential energy curves: triplets Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H

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

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

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

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

29. 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+(2s2p24P) 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: http://tcam.qui.uam.es Ion-Atom Collisions. Electron capture reactions in N2+, O2+ + H