A. A. Svinarenko

Radiative and collisional spectroscopy of hyperfine lines of the Li-like heavy ions and Tl atom in an atmosphere of inert gases

The combined relativistic energy approach and relativistic many-body perturbation theory with an optimized zeroth one-particle approximation are used for the calculation of the Li-like ions (Z = 11–42, 69, 70) and thallium atom spectral parameters of radiative transitions from the ground state to the excited state. A key feature of the presented approach is an implementation of the optimized relativistic model potential method in the framework of the energy approach for further studying the spectral and collisional characteristics of the multi-electron atoms. In addition, the method combined with the spectral line kinetic theory is used to study the hyperfine structure collision shift for the Tl atom in an atmosphere of inert gases.

Theoretical spectroscopy of autoionization resonances in spectra of lanthanide atoms

A theoretical study of the autoionization resonances in the spectra of lanthanide atoms (ytterbium) was carried out within the relativistic many-body perturbation theory and the generalized relativistic energy approach (the Gell-Mann and Low S-matrix formalism). The accurate results on the autoionization resonance energies and widths in ytterbium are presented with correctly accounting for the exchange correlation and relativistic corrections and are compared with the other available theoretical and experimental data.

QED Approach to Modeling Spectra of the Multicharged Ions in a Plasma: Oscillator and Electron‐ion Collision Strengths

The uniform energy approach, formally based on the QED theory with using gauge invariant scheme of generation of the optimal one‐electron representation, is used for the description of spectra of the multicharged ions in a laser plasma, calculation of electron‐ion collision strengths, cross‐sections in Ne‐like and Ar‐like ions.

Spectroscopy of Rydberg atoms in a Black-body radiation field: Relativistic theory of excitation and ionization

The combined relativistic energy approach and many-body perturbation theory with zeroth model potential approximation are used for computing Blackbody radiation ionization characteristics of the Rydberg atoms, in particular, the sodium in states with n=17,18,40-70. The calculated ionization rate values are compared with available theoretical and experimental data.

The Auger (Autoionization) Decay of Excited States in Spectra of Multicharged Ions: Relativistic Theory

Relativistic method of calculating the characteristics of the Auger decay in the atomic spectra, based on the S‐matrix Gell‐Mann and Low formalism, is used for estimating the transition energies and autoionization probabilities in spectra of the Fe ion with one vacancy above the core 1s22s22p63s23p6.

QED Approach to Atoms in a Laser Field: Multi-Photon Resonances and Above Threshold Ionization

A new consistent method for studying the interaction of atom with a realistic laser field, based on the quantum electrodynamics (QED) and S-matrix adiabatic formalism Gell-Mann and Low, is presented. In relativistic case the Gell-Mann and Low formula expressed an energy shift δE through QED scattering matrix including the interaction with as the laser field as the photon vacuum field. It is natural to describe the laser field-atom interaction by means of the radiation emission and absorption lines. Their position and shape fully determine the spectroscopy of atom in a field. The radiation atomic lines can be described by moments of different orders μn. The main contribution into μn is given by the resonant range. The values μn can be expanded into perturbation theory (PT) series. As example, the method is used for numerical calculation of the three-photon resonant, four-photon ionization profile of atomic hydrogen (1s-2p transition; wavelength = 365 nm) and multi-photon resonance width and shift for transition 6S-6F in the atom of Cs (wavelength 1,059 nm) in a laser pulses with the Gaussian and soliton-like shapes. The results of calculation the above threshold ionization (ATI) characteristics for atom of magnesium field are presented too.

Hyperfine Structure, Scalar‐pseudoscalar Interaction and Parity Non‐Conservation Effect in Some Heavy Atoms and Ions

The hyperfine structure parameters, scalar‐pseudoscalar interaction constants and parity non‐conservation effect in some heavy atomic systems are calculated and treated within the combined QED perturbation theory formalism and relativistic nuclear mean‐field theory.

Energy Approach to Nuclei and Atoms in a Strong Laser Field: Stark Effect and Multi-photon Resonances

A consistent energy approach to nuclei and atoms in a strong electromagnetic (laser) field is presented. The photon emission and absorption lines are described by the moments of different orders, which are calculated with the use of the Gell‐Mann and Low S‐matrix adiabatic formalism. In relativistic version the Gell‐Mann and Low formulae expresses an imaginary part of the energy shift ImE through the scattering matrix, including interaction of quantum system as with laser field as with a field of photon vacuum.

The Green’s Functions and Density Functional Approach to Vibrational Structure in the Photoelectron Spectra for Molecules

The combined theoretical approach to vibrational structure in photoelectron spectra (PES) of molecules, which is based on the density functional theory (DFT) and the Green’s‐functions (GF) approach, is used for quantitative treating the carbon oxide molecule PES.