| 1. |
- Andersson, Egil, et al.
(författare)
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Single-photon core-valence double ionization of molecular oxygen
- 2008
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 78, s. 023409-
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Tidskriftsartikel (refereegranskat)abstract
- Single-photon core-valence double ionization of molecular oxygen has been studied using a magnetic bottle time-of-flight electron coincidence spectrometer. The K-1V-1 double ionization electron spectrum of O-2 is reported and is assigned with the aid of ab initio calculations. A direct comparison of the core-valence double ionization electron spectra with the conventional valence band photoelectron spectrum is made. The lowest core-valence double ionization energy is found to be 571.6 eV and is associated with a (3)Pi dicationic state.
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| 2. |
- Brinne Roos, Johanna, 1976-, et al.
(författare)
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Dissociative recombination of HF
- 2008
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : The American Physical Society. - 1050-2947 .- 1094-1622. ; 78:2, s. 022508-1-022508-12
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Tidskriftsartikel (refereegranskat)abstract
- The direct mechanism of dissociative recombination of HF+ is studied usingboth time-dependent and time-independent methods, where the dynamics on 30resonant states is explored. The relevant electronic states are calculatedab initio by combining electron scattering calculations with multireference configurationinteraction structure calculations. For collision energies between 0.04 and 10 eV,we obtain qualitative agreement with experiment. At 1.9 eV there isa sharp threshold in both the experimental and theoretical crosssections that can be explained by the opening of newasymptotic limits. The measured cross section below 0.04 eV is notreproduced due to the neglect of the electronic couplings betweenthe neutral states. We examine the validity of the localapproximation for treating autoionization from the resonant states included inthis study.
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| 3. |
- Brinne Roos, Johanna, 1976-, et al.
(författare)
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Electron collisions with H3+: Ion-pair formation
- 2007
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : The American Physical Society. - 1050-2947 .- 1094-1622. ; 76:4, s. 042703-1-042703-9
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Tidskriftsartikel (refereegranskat)abstract
- The formation of the ion pair H2++H− in electron recombination with H3+ is studied. The diabatic potentials and electronic couplings are extracted from ab initio electron scattering calculations as well as quantum chemistry calculations. In order to describe this reaction we include six coupled electronic states and propagate wave packets in two dimensions using the multiconfiguration time-dependent Hartree method. Also, the cross section for ion-pair formation in electron recombination with D3+ is calculated. The cross section for this isotopomer is found to be about a factor of 3 smaller than the cross section for H3+.
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| 4. |
- Chourou, S. T., et al.
(författare)
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Low-energy dissociative electron attachment to CF2
- 2015
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 92:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of a theoretical study of dissociative electron attachment (DEA) of low-energy electrons to CF2. We carried out electron scattering calculations using the complex Kohn variational method at the static-exchange and relaxed self-consistent field (SCF) level at the equilibrium geometry and compare our differential cross sections to other results. We then repeated these calculations as a function of the three internal degrees of freedom to obtain the resonance energy surfaces and autoionization widths. We use this data as input to form the Hamiltonian relevant to the nuclear dynamics. The multidimensional wave equation is solved using the multiconfiguration time-dependent Hartree (MCTDH) approach within the local approximation.
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| 5. |
- Kalhori, S., et al.
(författare)
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Resonant ion-pair formation in electron collisions with rovibrationally cold H-3(+)
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 69:2, s. 022713-
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical cross sections for the resonant ion-pair formation (RIP) in electron collisions with rovibrationally cold H-3(+) ions are presented. Absolute cross sections for the RIP process producing H- ions are measured for center-of-mass energies between 2-20 eV using the CRYRING, heavy-ion storage ring. Theoretical cross sections are obtained using wave-packet propagation on both one- and two-dimensional models of relevant diabatic-potential energy surfaces and couplings of H-3(+) and H-3.
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| 6. |
- Larson, Åsa, et al.
(författare)
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Electronic resonant states of HCO and HOC
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 80:6, s. 62504-
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Tidskriftsartikel (refereegranskat)abstract
- The electronic resonant states of HCO and HOC are calculated using the complex Kohn variational method combined with structure calculations using multireference configuration interaction. No resonant state of HCO crosses the ion potential close to its minimum. Several resonances at higher energies are observed. There are clear indications of avoided crossings between the resonant states. There are resonant states that are repulsive with respect to both radial coordinates, but they remain relatively unchanged in energy as a function of the bending angle. For HOC, there are a manifold of resonant states with similar shapes as the potentials of HCO. However, the resonant states of HOC are lower in energy relative to the ion and could play an important role for dissociative recombination of HOC+ at low collision energies.
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| 7. |
- Larson, Åsa, et al.
(författare)
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Role of the direct mechanism in dissociative recombination of HCO+ and HOC
- 2012
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 85:4, s. 042702-
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Tidskriftsartikel (refereegranskat)abstract
- Studies of the direct mechanism for dissociative recombination of HCO+ and HOC+ are presented. The calculations involve wave-packet propagation in three dimensions on electronically resonant states of HCO and HOC with the potential-energy surfaces and autoionization widths obtained from ab initio electron scattering and electronic structure calculations. The total cross section and branching ratios for the two molecules and their deuterated isotopologues are calculated and compared to available experiments. The effect of vibrational excitation in DCO+ has been studied as well.
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| 8. |
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| 9. |
- Larson, Åsa, et al.
(författare)
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Wave-packet study of the products formed in dissociative recombination of HeH
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:3, s. 032701-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the atomic fragment distributions formed in dissociative recombination of HeH+ at low energies (< 2 eV) using wave packets propagating on the potential-energy curves of HeH, coupled by nonadiabatic and rotational interactions. We show that at zero electron collision energy, dissociation into H(n=2)+He will completely dominate over dissociation into the ground-state fragments. When the n=3 channel become energetically open at E=0.334 eV a rapid switchover to this channel will occur. This phenomenon has previously been observed experimentally, but here we present a theoretical model showing these jumps in the branching ratios. We present an explanation for the observed sudden change in branching ratios and we also discuss how the branching ratios depend on the nonadiabatic couplings used in the model.
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| 10. |
- Linusson, Per, et al.
(författare)
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Double photoionization of alcohol molecules
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 80:3, s. 32516-
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Tidskriftsartikel (refereegranskat)abstract
- The double valence photoionization spectra of methanol, ethanol, and n-propyl alcohol have been recorded using a time-of-flight photoelectron-photoelectron coincidence technique. The spectra show a well-defined onset followed by broad rounded bands. The lowest vertical double ionization energies have been determined for all molecules and are found to be 32.1, 29.6, and 28.2 eV, respectively. These energies have been applied along with single ionization energies from conventional photoelectron spectra to investigate a recently derived rule of thumb for determination of the lowest double ionization energy in molecules. Many-electron ab initio calculations have been performed on the dicationic ground states in good agreement with the experimental values. For methanol, also excited dicationic states have been calculated up to about 40 eV and used for a detailed interpretation of the experimental spectrum.
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