Abstract
The transition from the He atom to the complex atoms description in the method of interacting configurations in the complex number representation has been presented. As a first step the problem of ionization of H- and Li+ ions is considered. The spectroscopic characteristics of the Be, Mg and Ca atoms in the problem of the electron-impact ionization of these atoms are investigated. Few results in the photoionization problem on the 1P autoionizing states above the n=2 threshold of helium-like Be++ ion are presented. The energies and the widths of the lowest 1S; 1P; 1D; and 1F autoionizing states of the Be, Mg atoms, and the lowest (1P) autoionizing states of Ca atom, are calculated. We consider briefly both a review of our previous results (together with results of other authors) and new calculations of our group. A brief review of the methods of the quasi-stationary states calculation is given.
Highlights
Investigations of autoionization phenomena in the framework of the problems dealing with the ionization and the electron scattering by atoms and ions were separated in the last decades into an independent branch of theoretical atomic physics
The scientific interest to the description of the processes of excitation and decay of quasi-stationary states is associated with a necessity to specify the parameters of elementary processes, which are used in theoretical estimations and calculations in plasma physics, laser spectroscopy, solid state physics, and crystallography, at the development of technological methods of isotope separation at the atomic level, the designing of coherent ultra-violet and x-ray radiation generators, as well as in other physical domains
The results of experimental researches concerning the autoionizing states (AIS) located between the first and second ionization thresholds for helium and helium-like ions were qualitatively explained on the basis of the theory of isolated Fano resonance and in the diagonalization approximation
Summary
Investigations of autoionization phenomena in the framework of the problems dealing with the ionization and the electron scattering by atoms and ions were separated in the last decades into an independent branch of theoretical atomic physics. The appearance of new experimental data on resonance structures in partial cross-sections of helium photoionization above the threshold of excited ion formation (more exactly, in the interval between the second and third thresholds, to which the AIS energies converge in the atomic ionization problem) brought about a number of theoretical issues dealing, first of all, with the description of the interaction of a considerable number of overlapping quasi-stationary states, which decay through several open channels. An important step of the theory became the method of interacting configurations in the complex number representation (ICCNR method) This method was developed in works [1,2,3] and successfully applied to the description of the quasistationary states of helium formed at its electron ionization in the energy interval above the threshold of excited ion formation
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