Konstantin N. Lyashchenko
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Konstantin N. Lyashchenko has a total of 69 co-authors. Here are the top co-authors by number of shared publications:
- Oleg Yu. Andreev
St. Petersburg State University
18 shared publications - Deyang Yu
Institute of Modern Physics
9 shared publications - Daria M. Vasileva
Petersburg Nuclear Physics Institute
4 shared publications A. B. Voitkiv
Institute for Theoretical Physics I, Heinrich-Heine-University of Düsseldorf, Düsseldorf 40225, Germany
3 shared publications- Alexander B. Voitkiv
Heinrich-Heine-Universität Düsseldorf
3 shared publications O Yu Andreev
St. Petersburg State University
3 shared publications
Latest Publications
- 3 April 2026
- Published by American Physical Society (APS) in Physical Review A
- Vol. 113 (4)
Energy spectra of electron-positron pairs produced in bound-bound muon transitions
- 3 April 2026
- Published by American Physical Society (APS) in Physical Review A
- Vol. 113 (4)
Energy spectra of electron-positron pairs produced in bound-bound muon transitions
- 1 October 2025
- Published by IOP Publishing in Physica Scripta
- Vol. 100 (10) , 105405
Electron polarization in the resonant inelastic scattering on hydrogen-like ions
We investigate the polarization of the electron beam acquired during the inelastic resonant scattering on hydrogen-like ions initially being in the ground state. The formation and subsequent Auger decay of the intermediate ( 3 l 3 l ′ ) doubly excited states in the resonant channel modify the mechanism of polarization change by enhancing both spin-orbit and exchange interactions. Consequently, in the presence of the resonant channel, the acquired polarization can be clearly observed even for light ions when it is challenging to discern which state of the ion was excited in the process. We also show that the energy dependence of the polarization parameter clearly demonstrates strong interference both between the contributions of specific autoionizing states in the resonant channel and between the non-resonant and resonant channels.
- 1 October 2025
- Published by IOP Publishing in Physica Scripta
- Vol. 100 (10) , 105405
Electron polarization in the resonant inelastic scattering on hydrogen-like ions
We investigate the polarization of the electron beam acquired during the inelastic resonant scattering on hydrogen-like ions initially being in the ground state. The formation and subsequent Auger decay of the intermediate ( 3 l 3 l ′ ) doubly excited states in the resonant channel modify the mechanism of polarization change by enhancing both spin-orbit and exchange interactions. Consequently, in the presence of the resonant channel, the acquired polarization can be clearly observed even for light ions when it is challenging to discern which state of the ion was excited in the process. We also show that the energy dependence of the polarization parameter clearly demonstrates strong interference both between the contributions of specific autoionizing states in the resonant channel and between the non-resonant and resonant channels.
- 20 March 2025
- Published by American Physical Society (APS) in Physical Review A
- Vol. 111 (3)
Photon angular distribution in two-photon electron capture by H-like uranium
- 20 March 2025
- Published by American Physical Society (APS) in Physical Review A
- Vol. 111 (3)
Photon angular distribution in two-photon electron capture by H-like uranium
- 30 October 2024
- Published by IOP Publishing in Physica Scripta
- Vol. 99 (11) , 115410
Inelastic resonant scattering of electrons on hydrogen-like ions
The inelastic electron scattering is one of the processes that must be understood in detail for the correct interpretation of astrophysical data. We suggest ab initio QED treatment of the inelastic scattering of quasi-free electrons on hydrogen-like ions with possible formation and subsequent decay of intermediate autoionizing states. We calculate the doubly differential cross sections for scattering on F8+, Ca19+ and Kr35+ in the range of energies where doubly excited 3 l 3 l ′ states are involved. The energies and widths of these states are presented.
- 30 October 2024
- Published by IOP Publishing in Physica Scripta
- Vol. 99 (11) , 115410
Inelastic resonant scattering of electrons on hydrogen-like ions
The inelastic electron scattering is one of the processes that must be understood in detail for the correct interpretation of astrophysical data. We suggest ab initio QED treatment of the inelastic scattering of quasi-free electrons on hydrogen-like ions with possible formation and subsequent decay of intermediate autoionizing states. We calculate the doubly differential cross sections for scattering on F8+, Ca19+ and Kr35+ in the range of energies where doubly excited 3 l 3 l ′ states are involved. The energies and widths of these states are presented.
- 4 March 2024
- Published by American Physical Society (APS) in Physical Review A
- Vol. 109 (3) , 032805
Two-photon electron capture by H-like uranium
We present a study of two-photon electron capture by H-like uranium ions. The energy of the incident electron was chosen to be in the region with the most significant contribution of the dielectronic recombination. We studied the photon emission spectrum. In particular, we calculated the differential over the photon energy cross section including the main resonance groups corresponding to the cascade transitions, and the low-energy photon region, where the infrared divergence required special processing. The calculations were performed within the framework of QED theory. The importance of generalized Breit interaction was discussed. We investigated the roles of the dielectronic recombination and the radiative recombination. We investigated the resonance approximation and the single-photon approximation, which are commonly used to describe radiation spectra.
- 4 March 2024
- Published by American Physical Society (APS) in Physical Review A
- Vol. 109 (3) , 032805
Two-photon electron capture by H-like uranium
We present a study of two-photon electron capture by H-like uranium ions. The energy of the incident electron was chosen to be in the region with the most significant contribution of the dielectronic recombination. We studied the photon emission spectrum. In particular, we calculated the differential over the photon energy cross section including the main resonance groups corresponding to the cascade transitions, and the low-energy photon region, where the infrared divergence required special processing. The calculations were performed within the framework of QED theory. The importance of generalized Breit interaction was discussed. We investigated the roles of the dielectronic recombination and the radiative recombination. We investigated the resonance approximation and the single-photon approximation, which are commonly used to describe radiation spectra.
- 15 July 2022
- Published by American Physical Society (APS) in Physical Review A
- Vol. 106 (1) , 012809
Investigation of two-photon decay in one-electron and one-muon ionsWe study the radiative decay of the state of one-electron and one-muon ions, where the two-photon mechanism plays an important role. Due to the nuclear size corrections, the radiative decay of the state in the electron and muon ions is qualitatively different. Based on the accurate relativistic calculation, we introduce a two-parameter approximation, which makes it possible to describe the two-photon angular-differential transition probability for the polarized emitted photons with high accuracy. The emission of photons with linear and circular polarizations is studied separately. We also investigate the transition probabilities for the polarized initial and final states. The investigation is performed for ions with atomic numbers .- 15 July 2022
- Published by American Physical Society (APS) in Physical Review A
- Vol. 106 (1) , 012809
Investigation of two-photon decay in one-electron and one-muon ionsWe study the radiative decay of the state of one-electron and one-muon ions, where the two-photon mechanism plays an important role. Due to the nuclear size corrections, the radiative decay of the state in the electron and muon ions is qualitatively different. Based on the accurate relativistic calculation, we introduce a two-parameter approximation, which makes it possible to describe the two-photon angular-differential transition probability for the polarized emitted photons with high accuracy. The emission of photons with linear and circular polarizations is studied separately. We also investigate the transition probabilities for the polarized initial and final states. The investigation is performed for ions with atomic numbers .- 11 November 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (5) , 052808
Resonant elastic scattering of polarized electrons on H-like ions
We study the polarization properties of elastic electron scattering on H-like ions using the relativistic QED theory. We calculate the complete set of parameters which describe the scattering of a polarized electron on an initially unpolarized ion and analyze them for both nonresonant and resonant scattering focusing on the LL-shell resonances. The study is carried out for , and ions. We demonstrate that for the resonant electron scattering on ions with up to 50 both the relativistic spin-orbit and the exchange interaction are equally significant. The possible spin exchange between the incident and bound electrons can fundamentally change the polarization of the scattered electron. We show that the involvement of the autoionizing states leads to quantitative and qualitative changes in the polarization parameters, in particular, to a significant increase in the spin asymmetry.- 11 November 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (5) , 052808
Resonant elastic scattering of polarized electrons on H-like ions
We study the polarization properties of elastic electron scattering on H-like ions using the relativistic QED theory. We calculate the complete set of parameters which describe the scattering of a polarized electron on an initially unpolarized ion and analyze them for both nonresonant and resonant scattering focusing on the LL-shell resonances. The study is carried out for , and ions. We demonstrate that for the resonant electron scattering on ions with up to 50 both the relativistic spin-orbit and the exchange interaction are equally significant. The possible spin exchange between the incident and bound electrons can fundamentally change the polarization of the scattered electron. We show that the involvement of the autoionizing states leads to quantitative and qualitative changes in the polarization parameters, in particular, to a significant increase in the spin asymmetry.- 13 September 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (3) , 032815
State-selective nonradiative electron capture in collisions of with Kr and XeLyman transitions of produced by nonradiative electron capture in collisions of 95, 146, and 197 ions with Kr and Xe atoms have been studied experimentally. It shows that the captured electrons preferentially populate lower states. The intensity ratios and are found to decrease with increasing projectile velocity, and the ratios for Xe decrease faster than those of Kr. The obtained results are compared with the relative cross sections calculated with the relativistic eikonal approximation. For both targets, the theoretical results overestimate the experimental ratio but underestimate Moreover, the theory gives parallel decreasing curves for the two targets, which does not agree with the present experiment. In order to well understand the experimental findings, a more sophisticated theoretical approach is urgently required.- 13 September 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (3) , 032815
State-selective nonradiative electron capture in collisions of with Kr and XeLyman transitions of produced by nonradiative electron capture in collisions of 95, 146, and 197 ions with Kr and Xe atoms have been studied experimentally. It shows that the captured electrons preferentially populate lower states. The intensity ratios and are found to decrease with increasing projectile velocity, and the ratios for Xe decrease faster than those of Kr. The obtained results are compared with the relative cross sections calculated with the relativistic eikonal approximation. For both targets, the theoretical results overestimate the experimental ratio but underestimate Moreover, the theory gives parallel decreasing curves for the two targets, which does not agree with the present experiment. In order to well understand the experimental findings, a more sophisticated theoretical approach is urgently required.- 29 July 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (1) , 012818
QED calculation of two-electron one-photon transition probabilities in He-like ions
We consider theoretically the process of two-electron one-photon (TEOP) transitions to the ground state with the emission of a single photon in a He-like sequence of atomic ions: from boron to uranium. The corresponding transition probabilities and transition energies are calculated within the QED theory. The calculations of the transition probabilities are performed in various gauges. The intensity ratios between the TEOP transitions and the other major transitions are presented.- 29 July 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (1) , 012818
QED calculation of two-electron one-photon transition probabilities in He-like ions
We consider theoretically the process of two-electron one-photon (TEOP) transitions to the ground state with the emission of a single photon in a He-like sequence of atomic ions: from boron to uranium. The corresponding transition probabilities and transition energies are calculated within the QED theory. The calculations of the transition probabilities are performed in various gauges. The intensity ratios between the TEOP transitions and the other major transitions are presented.- 19 July 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (1) , 012809
Electron-loss-to-continuum cusp in collisions of with and XeWe study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of projectiles in collisions with and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of . Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.- 19 July 2021
- Published by American Physical Society (APS) in Physical Review A
- Vol. 104 (1) , 012809
Electron-loss-to-continuum cusp in collisions of with and XeWe study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of projectiles in collisions with and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of . Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.