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| 2. |
- Erman, P., et al.
(författare)
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Non Franck-Condon effects in photoionization of molecular oxygen
- 2000
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Ingår i: Physica scripta. T. - 0281-1847. ; 62:4, s. 294-300
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical and experimental analysis of non Franck-Condon effects in photoionization to the b (4)Sigma(g)(-), state of O-2(+). Experimentally, by dispersing the synchrotron radiation induced O-2(+) b (4)Sigma(g)(-) a (IIu)-I-4 fluorescence we derive the b (4)Sigma(g)(-), State vibrational branching ratios in the excitation energy range 21-34 eV. The vibrational branching ratios reveal features in the region 21-28 eV indicating strong non Franck-Condon effects. The experimental results have been analysed by computing ab initio the vibrational population branching ratios using a many-body perturbation method. Additionally the autoionizing neutral states existing in this energy region have been studied. We have computed the energies of the valence states up to an energy of 30 eV their transition moments for excitations from the ground state, and autoionization rates. Our calculations show, that strong non Franck-Condon effects recorded in the branching ratio spectrum (below 25 eV) are actually caused by the narrow 3 sigma(g) --> sigma(u) shape resonance, and its coupling to the 1 pi(u) --> pi(g) channel.
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| 3. |
- Karawajczyk, A., et al.
(författare)
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Neutral fragmentation of superexcited oxygen molecules
- 2000
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 61:3, s. art. no.-32718
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of neutral dissociation of oxygen molecules in the excitation energy range 15-25 eV have been studied in a dispersed fluorescence experiment. By detecting the fluorescence from excited oxygen atoms, we find that neutral superexcited O-2 states below 20 eV dissociate into O(g.s.) + O(3s,3p). At higher excitation energies (h nu = 20-25 eV) the curve-crossing interactions following excitations to members of the Rydberg c (4)Sigma(u)(-) series also yield atoms in Rydberg states (nl,n greater than or equal to 4). The experimental data are analyzed on the ground of many-body perturbation theory, calculations which indicate the structure of the predissociating states converging to the experimentally observed ones.
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| 4. |
- Kukk, E., et al.
(författare)
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Dissociation of deuteromethane following carbon 1s core ionization
- 2002
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 66:1
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Tidskriftsartikel (refereegranskat)abstract
- Energy-resolved electron-ion coincidence spectra of the deuteromethane molecule were measured following ionization by narrow-band synchrotron radiation. The ion mass spectra were recorded in coincidence with the outer and inner valence photoelectrons and with the normal Auger electrons from the decay of the carbon 1s core hole. Complementary noncoincidence ion mass spectra were measured below and above the C 1s threshold. The fragmentation patterns of the singly and doubly ionized deuteromethane under different ionization conditions are examined. Carbon core ionization is shown to open new photodissociation pathways not available in the valence ionization photon energy regime. With the aid of ab initio quantum chemistry calculations, a two-step model of the dissociation following core ionization is proposed, showing a good agreement with the experimental findings.
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