| 1. |
- Fogle, M., et al.
(författare)
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Electron-impact ionization of Be-like CIII, NIV, and OV
- 2008
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 175:2, s. 543-556
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Tidskriftsartikel (refereegranskat)abstract
- We present recent measurements of absolute electron-impact ionization cross sections for Be-like C III, N IV, and O V forming Li- like C IV, N V, and O VI. The measurements were taken using the crossed-beams apparatus at Oak Ridge National Laboratory. A gas cell beam attenuation method was used to independently measure the metastable fractions present in the ion beams. The measured ionization cross sections were compared with calculations using the R-matrix with pseudostates and distorted-wave theoretical methods. Best agreement is found with the R-matrix with pseudostates cross sections results that account for the metastable fractions inferred from the gas attenuation measurements. We present a set of recommended rate coefficients for electron-impact single ionization from the ground state and metastable term of each ion.
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| 2. |
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| 3. |
- Bahati, E. M., et al.
(författare)
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Electron-impact dissociation of CD3+ and CH3+ ions producing CD2+, CH+ and C+ fragment ions
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 79:5, s. 52703-
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Tidskriftsartikel (refereegranskat)abstract
- Using a crossed electron-ion beams method, we measured absolute cross sections for electron-impact dissociation of the CD3+ molecular ions producing CD2+ fragment ions and CH3+ ions yielding CH+ and C+ fragment ions over a collision energy range from a few eV up to 100 eV. The total experimental uncertainties are about 12% at the maximum of the curves of cross sections (peak of the cross section for the CH+ channel). The obtained results suggest important roles played by predissociation of bound states in the production of both the CH+ and C+ fragment ions. Good agreement is found with other results reported for the CH+ fragment, but some differences are found for the CD2+ and C+ fragments.
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| 4. |
- Hellberg, F, et al.
(författare)
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Investigating the breakup dynamics of dihydrogen sulfide ions recombining with electrons
- 2005
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 122:22, s. 224314-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results concerning measurements of the dissociative recombination (DR) of dihydrogen sulfide ions. In combination with the ion storage ring CRYRING an imaging technique was used to investigate the breakup dynamics of the three-body channel in the DR of (SD2+)-S-32. The two energetically available product channels S(P-3)+2D(S-2) and S(D-1)+2D(S-2) were both populated, with a branching fraction of the ground-state channel of 0.6(0.1). Information about the angle between the two deuterium atoms upon dissociation was obtained together with information about how the available kinetic energy was distributed between the two light fragments. The recombination cross sections as functions of energy in the interval of 1 meV to 0.3 eV in the center-of-mass frame are presented for (SH2+)-S-34. The thermal rate coefficient for the DR of (SH2+)-S-34 was determined to be (4.8 +/- 1.0)x10(-7)(T/300)(-0.72 +/- 0.1) cm(3) s(-1) over this interval.
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| 5. |
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| 6. |
- Zhaunerchyk, V., et al.
(författare)
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Three-body breakup in the dissociative recombination of the covalent triatomic molecular ion O-3(+)
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:22, s. 223201-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of almost exclusive three-body breakup in the dissociative recombination of a covalent triatomic molecular ion O-3(+). The three-body channel, constituting about 94% of the total reactivity, has been investigated in detail. The atomic fragments are formed in only the first two electronic states, P-3 and D-1, while formation in the S-1 state has not been observed. The breakup predominantly proceeds through dissociative states with linear geometry.
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| 7. |
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| 8. |
- Vane, C. R., et al.
(författare)
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Electron-impact dissociation of CH2+ ions : Measurement of CH+ and C+ fragment ions
- 2007
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 75:5, s. 52715-
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Tidskriftsartikel (refereegranskat)abstract
- Absolute cross sections for electron-impact dissociation of CH2+ producing CH+ and C+ fragment ions were measured in the 3-100 eV range using a crossed electron-ion beams technique with total uncertainties of about 11% near the cross section peak. The cross sections are nearly identical for energies above 15 eV, but they are dramatically different at lower energies. The CH+ channel exhibits a strong peak rising from an observed threshold of about 6 eV; the C+ channel is relatively flat down to the lowest measured energy. Ionization cross sections for the CH2+ ion are also presented.
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| 9. |
- Zhaunerchyk, Vitali, et al.
(författare)
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Dissociative recombination study of PD2+ at CRYRING : absolute cross-section, chemical branching ratios and three-body fragmentation dynamics
- 2005
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Ingår i: Molecular Physics. - : Informa UK Limited. - 0026-8976 .- 1362-3028. ; 103:20, s. 2735-2745
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Tidskriftsartikel (refereegranskat)abstract
- The paper reports an investigation of the dissociative recombination of PD2+ at the heavy-ion storage ring CRYRING. The absolute cross-section has been measured as a function of centre-of-mass energy ranging from 1 meV to 0.1 eV. The experiment performed has shown the dissociative recombination of PD2+ to be dominated by three-body break-up, with a branching ratio of about 78%. Competition between the available three-body channels producing the ground state, P(S-4), and the. first two excited states, P(D-2) and P(P-2), is observed. The formation of the first excited state dominates over the other two almost equally probable channels with about 75% of all three-body events. The results indicate that the kinetic energy released in the three-body break- up of PD2+ is randomly shared between the deuterium atoms. The intra-molecular angle on dissociation has also been investigated. A comparative analysis of the dissociative recombination dynamics for the two isovalent systems, PD2+ and NH2+, is undertaken.
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