Investigations of the breakup dynamics of small molecular ions recombining with electrons

Dissociative recombination is the process in which a molecular ion recombines with an electron and then fragments into neutral products. This process has been studied in many experiments over the years at the ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm University. In this thesis the experimental methods and data analysis procedures used to investigate dissociative recombination are presented together with the results for several diatomic and triatomic ions. Cross sections and branching fractions of the different breakup channels have been determined. An imaging system was introduced to study the fragmentation channels in detail. The main focus is on the dynamics of the three-body breakup of triatomic dihydride ions. This work includes the results from the dissociative recombination of NO, SH2 , SD + 2 , PD + 2 , NH + 2 , CH + 2 , H2O + and H3 . List of Publications I. Dissociative recombination of NO: Dynamics of the XΣ and aΣ electronic states. F. Hellberg, S. Rosén, R. Thomas, A. Neau, M. Larsson, A. Petrignani, and W. J. van der Zande. Journal of Chemical Physics 118, 6250 (2003). II. Investigating the breakup dynamics of dihydrogen sulfide ions recombining with electrons. F. Hellberg, V. Zhaunerchyk, A. Ehlerding, W. D. Geppert, M. Larsson, R. D. Thomas, M. E. Bannister, E. Bahati, C. R. Vane, F. Österdahl, P. Hlavenka and M. af Ugglas. Journal of Chemical Physics 122, 224314 (2005). III. Three-body fragmentation dynamics of amidogen and methylene radicals via dissociative recombination. R. D Thomas, F. Hellberg, A. Neau, S. Rosén, M. Larsson, C. R. Vane, M. E. Bannister, S. Datz, A. Petrignani, and W. J. van der Zande. Physical Review A 71, 032711 (2005). IV. Dissociative recombination study of PD2 at CRYRING: Absolute cross section, chemical branching ratios and three-body fragmentation dynamics. V. Zhaunerchyk, F. Hellberg, A. Ehlerding, W. D. Geppert, M. Larsson, C. R. Vane, M. E. Bannister, E. M. Bahati, F. Österdahl, M. af Ugglas, and R. D. Thomas. Molecular Physics 20, 2735 (2005). V. Investigating the three-body fragmentation dynamics of water via dissociative recombination and theoretical modeling calculations. R. Thomas, S. Rosén, F. Hellberg, A. M. Derkach, M. Larsson, S. Datz, R. Dixon, and W. J. van der Zande. Physical Review A 66, 032715 (2002). VI. Dissociative recombination of rotationally cold H3 . B. J. McCall, A. J. Hunneycutt, R. J. Saykelly, N. Djuric, H. C. Dunn, J. Semaniac, O. J. Novotny, A. Al-Khalili, A. Ehlerding, F. Hellberg, S. Kalhori, A. Neau, R. Thomas, F. Österdahl, and M. Larsson. Physical Review A 70, 052716 (2004). The following publications are not discussed in this thesis: 1. Dynamics of three-body breakup in dissociative recombination: H2O . S. Datz, R. Thomas, S. Rosén, M. Larsson, A. M. Derkach, F. Hellberg, and W. J. van der Zande. Physical Review Letters 85, 5555 (2000). 2. Dissociative recombination of HCNH: Absolute cross-sections and branching ratios. J. Semaniak, B. F. Minaev, A. M. Derkatch, F. Hellberg, A. Neau, S. Rosén, R. Thomas, M. Larsson, H. Danared, A. Paal, and M. af Ugglas. The Astrophysical Journal Supplement Series 135, 275 (2001). 3. Electron-impact detachment and dissociation of C4 ions. A. Le Padellec, F. Rabilloud, D. Pegg, A. Neau, F. Hellberg, R. Thomas, H. T. Schmidt, M. Larsson, H. Danared, A. Källberg, K. Andersson, and D. Hanstorp. Journal of Chemical Physics 115, 10671 (2001). 4. Electron scattering on CN−. A. Le Padellec, K. Andersson, D. Hanstorp, F. Hellberg, M. Larsson, A. Neau, S. Rosén, H. T. Schmidt, R. Thomas, J. Semaniak, D. J. Pegg, F. Österdahl, H. Danared, and A. Källberg. Physica Scripta 64, 467 (2001). 5. Photoelectron spectroscopy of nickel, palladium and platinum oxide anions. T. M. Ramond, G. E. Davico, F. Hellberg, F. Svedberg, P. Salén, P. Söderqvist, and W. C. Lineberger. Journal of Molecular Spectroscopy 216, 1 (2002). 6. Resonant ion pair formation of HD: Absolute cross sections for the H− + D channel. A. Neau, A. M. Derkach, F. Hellberg, S. Rosén, R. Thomas, M. Larsson, J. Semaniak, N. Djuric, D. B. Popovic, and G. H. Dunn. Physical Review A 65, 044701 (2002). 7. Relative cross sections for the electron impact single detachment on Li−. A. Le Padellec, C. F. Collins, H. Danared, A. Källberg, F. Hellberg, A. Neau, K. Fritioff, D. Hanstorp, and M. Larsson. Journal Physical B 35, 3669 (2002). 8. Studies of dissociative recombination in CRYRING. M. Larsson, N. Djuric, G. H. Dunn, A. Neau, A. M. Derkatch, F. Hellberg, S. Kalhori, D. Popovic, J. Semaniak, Å. Larson, and R. Thomas. Dissociative recombination of molecular ions with electrons, edited by S. L. Guberman (Kluwer Academic/Plenum publichers, New York, 2003). 9. Recent studies of three-body fragmentation dynamics via disociative recombination in CRYRING. R. Thomas, S. Datz, M. Larsson, W. J. van der Zande, F. Hellberg, A. Petrignani, S. Rosén, A. M. Derkach, A. Neau, and C. R. Vane. Dissociative recombination of molecular ions with electrons, edited by S. L. Guberman (Kluwer Academic/Plenum publichers, New York, 2003). 10. Electron collisions with C4 : Detachment process and resonant structure. A. Le Padellec, F. Rabilloud, D. Pegg, K. Andersson, D. Hanstorp, A. Neau, M. Larsson, F. Hellberg, and R. Thomas. Dissociative recombination of molecular ions with electrons, edited by S. L. Guberman (Kluwer Academic/Plenum publichers, New York, 2003). 11. Infrared cavity ringdown spectroscopy of acid-water clusters: HCl-H2O, DCl-D2O, and DCl-(D2O)2. A. J. Huneycutt, R. J. Stickland, F. Hellberg, R. J. Saykally. Journal of Chemical Physics 118, 1221 (2003). 12. An enhanced cosmic-ray flux towards ζ Persei inferred from a laboratory study of the H3 e − recombination rate. B. J. McCall, A. J. Huneycutt, R. J. Saykally, T. R. Geballe, N. Djuric, G. H. Dunn, J. Semaniak, O. Novotny, A. Al-Khalili, A. Ehlerding, F. Hellberg, S. Kalhori, A. Neau, R. Thomas, F. Österdahl, and M. Larsson. Nature 422, 500 (2003). 13. Electron-impact detachment from S−. K. Fritioff, J. Sandström, D. Hanstorp, F. Hellberg, A. Ehlerding, M. Larsson, C. F. Collins, D. J. Pegg, H. Danared, A. Källberg. European Physical Journal D 27, 23 (2003). 14. Single and double detachment of H−. K. Fritioff, J. Sandström, P. Andersson, D. Hanstorp, F. Hellberg, R. Thomas, W. Geppert, M. Larsson, F. Österdahl, C. F. Collins, D. J. Pegg, H. Danared, A. Kjällberg, N. D. Gibson. Physical Review A 69, 042707 (2004). 15. Dissociative recombination of C2H + and C2H + 4 : Absolute cross sections and product branching ratios. A. Ehlerding, F. Hellberg, R. Thomas, S. Kalhori, A. A. Viggiano, S. T. Arnold, M. Larsson, M. af Ugglas. Physical Chemistry Chemical Physics 6, 949 (2004). 16. Dissociative recombination of SO2 : evidence for three-body break-up. W. D. Geppert, F. Hellberg, A. Ehlerding, J. Semaniak, F. Österdahl, M. Kaminska, V. Zhaunerchyk, A. Al-Khalili, M. af Ugglas, R. Thomas, A. Källberg, M. Larsson. The Astrophysical Journal 610, 1228 (2004). 17. Dissociative recombination of C3H + 4 : preferential formation of the C3H + 4 radical. W. D. Geppert, R. Thomas, A. Ehlerding, F. Hellberg, F. Österdahl, M. af Ugglas, and M. Larsson. International Journal of Mass Spectrometry 237, 25 (2004). 18. First observation of four-body break-up in electron recombination: C2D + 5 . W. D. Geppert, A. Ehlerding, F. Hellberg, S. Kalhori, R. D. Thomas, O. Novotny, S. T. Arnold, T. M. Miller, A. A. Viggiano, and M. Larsson. Physical Review Letters 93, 153201-1 (2004). 19. Dissociative recombination of nitrile ions: DCCCN and DCCCND. W. D. Geppert, A. Ehlerding, F. Hellberg, J. Semaniak, F. Österdahl, M. Kaminska, A. Al-Khalili, V. Zhaunerchyk, R. Thomas, M. af Ugglas, A. Källberg, A. Simonsson, and M. Larsson. The Astrophysical Journal 613, 1302 (2004). 20. Dissociative recombination study of Na(D2O) in a storage ring. V. Zhaunerchyk, A. Ehlerding, W. D. Geppert, F. Hellberg, R. D. Thomas, M. Larsson, A. A. Viggiano, S. T. Arnold, F. Österdahl, and P. Hlavenka. Journal of Chemical Physics 121, 10483 (2004). 21. Dissociative recombination cross-section and branching ratios of protonated dimethyl disulphide and N-methyl acetamide. A. Al-Khalili, E. Uggerud, R. Zubarev, J. Semaniak, P.Andersson, V. Bednarska, A. Ehlerding, W. D. Geppert, F. Hellberg, M. Kaminska, F. Kjeldsen, A. Paal, R. Thomas, M. af Ugglas, J. Vedde, V. Zhaunerchyk, F. Österdahl, and M. Larsson. Journal of Chemical Physics 121, 5700 (2004). 22. Resonant ion-pair in electron collisions with rovibrationally cold H3 . S. Kalhori, R. Thomas, A. Al-Khalili, A. Ehlerding, F. Hellberg, A. Neau, M. Larsson, Å. Larsson, A. J. Hunneycut, B. J. McCall, N. Djuric, H. C. Dunn, J. Semaniac, O. J. Novotny, A. Paal, F. Österdahl, A. E. Orel. Physical Review A 69, 022713 (2004). 23. The dissociative recombination of N2OD . W. D. Geppert, R. Thomas, F. Hellberg, F. Österdahl, A. Ehlerding, M. af Ugglas, M. Larsson. Physical Chemistry Chemical Physics 6, 3415 (2004). 24. Dissociative recombination branching ratios and their influence on interstellar clouds. W. D. Geppert, R. D. Thomas, A. Ehlerding, F. Hellberg, F. Österdahl, M. Hamberg, J. Semaniak, V. Zhaunerchyk, M. Kaminska, A. Källberg, A. Paal, and M. Larsson. Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications, edited by Andreas Wolf, Lutz Lammich, Peter Schmelcher, (Institute of Physics Publishing, Bristol and Philadelphia, 2005), Vol. IV. 25. Storage ring measurements of the dissociative recombination rate of rotationally cold H3 . B. J. McCall, A.J. Huneycutt, R.J. Saykally, N. Djuric, G. H. Dunn, J. Semaniak, O. Novotny, A. Al-Khalili, A. Ehlerding, F. Hellberg, S. Kalhori, A. Neau, R. Thomas, F. Österdahl, and M. Larsson. Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications, edited by Andreas Wolf, Lutz Lammich, Peter Schmelcher, (Institute of Physics Publishing, Bristol and Philadelphia, 2005), Vol. IV. 26. Vibrational dependence in the dissociative recombination of O2 . A. Petrignani, F. Hellberg, R. D Thomas, M. Larsson, P. C. Cosby, and W. J. van der Zande. Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications, edited by Andreas Wolf, Lutz Lammich, Peter Schmelcher, (Institute of Physics Publishing, Bristol and Philadelphia, 2005), Vol. IV. 27. The effect on bonding on the fragmentations of small systems. R. D. Thomas, A. Ehlerding, W. Geppert, F. Hellberg, M. Larsson, V. Zhaunerchyk, E. Bahati, M. E. Bannister, C. R Vane, A. Petrignani, W. J. van der Zande, P. Andersson, and J. B. C. Pettersson. Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications, edited by Andreas Wolf, Lutz Lammich, Peter Schmelcher, (Institute of Physics Publishing, Bristol and Philadelphia, 2005), Vol. IV. 28. Positionand time-sensitive coincident detection of fragments from the dissociative recombination of O2 using a single hexanode delay-line detector. F. Österdahl, S. Rosén, V. Bednarska, A. Petrignani, F. Hellberg, M. Larsson, and W. J. van der Zande. Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications, edited by Andreas Wolf, Lutz Lammich, Peter Schmelcher, (Institute of Physics Publishing, Bristol and Philadelphia, 2005), Vol. IV. 29. Branching ratios and absolute cross sections of the dissociative recombination of N2O . M. Hamberg, W. D. Geppert, S. Rosén, A. Ehlerding, F. Hellberg, V. Zhaunerchyk, M. Kaminska, R. Thomas, A. Källberg, A. Simonsson, A. Paal, and M. Larsson. Physical Chemistry Chemical Physics, 7, 1664 (2005). 30. Vibrationally resolved rate coefficients and branching fractions in the dissociative recombination of O2 . A. Petrignani, W. J. van der Zande, P. C. Cosby, F. Hellberg, R. D. Thomas, and M. Larsson. Journal of Chemical Physics 122, 014302 (2005). 31. Branching ratios for the dissociative recombination of C3D + 7 and C4D + 9 . M. Larsson, A. Ehlerding, W. D. Geppert, F. Hellberg, S. Kalhori, R. D. Thomas, N. Djuric, F. Österdahl, G. Angelova, J. Semaniak, O. Novotny, S. T. Arnold, A. A. Viggiano. Journal of Chemical Physics 122, 156101 (2005). 32. Rate constants and branching ratios for the dissociative recombination of CO2 . A. A. Viggiano, A. Ehlerding, F. Hellberg, R. D. Thomas, V. Zhaunerchyk, W. D. Geppert, H. Montaigne, M. Larsson, M. Kaminska, and F. Österdahl. Journal of Chemical Physics 122, 226101 (2005). 33. Electron energy-dependent product state distributions in the dissociative recombination of O2 . A. Petrignani, F. Hellberg, R. D. Thomas, M. Larsson, P. C. Cosby, and W. J. van der Zande. Journal of Chemical Physics 122, 234311 (2005). 34. Dissociative recombination of the thioformyl (HCS) and carbonyl sulfide (OCS) cations. H. Montaigne, W. D. Geppert, J. Semaniak, F. Oesterdahl, F. Hellberg, R. D. Thomas, M. af Ugglas, H. Roberts, T. J. Millar, V. Zhaunerchyk, M. Kaminska, A. Al-Khalili, A. Källberg, and M. Larsson. The Astrophysical Journal 631, 653 (2005). Contributions from the author During the five years of my Ph.D. studies I have participated in many experiments, which have resulted in a number of publications (see list of publications). My contributions to all of these experiments have been to set-up the detector systems and to collect the experimental data. This was done together with several collegues. In this thesis six papers are included in which my contributions have exceeded the experimental work. My main responsibility in the experimental work of Paper I-IV was to set-up the imaging system. In Paper I-II, I analyzed the experimetal data, and I was responsible for writing both papers. InPaper I, I also performed some ab initio calculations. In Paper III, I analyzed the data from the chemical branching fractions of NH2 . In Paper VI, I analyzed the data from the measurements of the chemical branching fractions and I have written section III.C.