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- Nikolić, Dragan, 1968-
(författare)
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Autoionizing states and their relevance in electron-ion recombination
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atomic physics plays an important role in determining the evolution stages in a wide range of laboratory and cosmic plasmas. Therefore, the main contribution to our ability to model, infer and control plasma sources is the knowledge of underlying atomic processes. Of particular importance are reliable low temperature dielectronic recombination (DR) rate coefficients.This thesis provides systematically calculated DR rate coefficients of lithium-like beryllium and sodium ions via ∆n = 0 doubly excited resonant states. The calculations are based on complex-scaled relativistic many-body perturbation theory in an all-order formulation within the single- and double-excitation coupled-cluster scheme, including radiative corrections.Comparison of DR resonance parameters (energy levels, autoionization widths, radiative transition probabilities and strengths) between our theoretical predictions and the heavy-ion storage rings experiments (CRYRING-Stockholm and TSRHeidelberg) shows good agreement.The intruder state problem is a principal obstacle for general application of the coupled-cluster formalism on doubly excited states. Thus, we have developed a technique designed to avoid the intruder state problem. It is based on a convenient partitioning of the Hilbert space and reformulation of the conventional set of pairequations. The general aspects of this development are discussed, and the effectiveness of its numerical implementation (within the non-relativistic framework) is selectively illustrated on autoionizing doubly excited states of helium.
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| 2. |
- Nikolić, Dragan, et al.
(författare)
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Dielectronic recombination resonances in Na8
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : The American Physical Society. - 1050-2947 .- 1094-1622. ; 70:6
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Tidskriftsartikel (refereegranskat)abstract
- The electron-ion recombination spectrum of the Li-like Na8+ ion in the energy range 0.0–0.5 eV is presented. Experimental results obtained by storage-ring techniques are compared with a calculated spectrum, based on a combination of relativistic many-body methods and complex rotation, and the agreement is found to be very good. The deviations between measured and calculated dielectronic recombination resonance energies are usually below about 2 meV with a maximum difference at 5.5 meV, while the theoretical cross sections deviate by at most 20% from the experiment. The recombination spectrum in the investigated energy region is determined by the 2pj7ℓj′ Rydberg manifold of dielectronic recombination resonances, comprising 61 states within half an eV above the ground state of Na8+. The theoretical resonance parameters of all contributing states are provided.
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