Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Atomic Molecular Condensate and Nano Physics

Bremsstrahlung of Fast Electrons Near Fano Resonance with Account for Polarization Channel

FRANK B. ROSMEJ, Valery Alexandrovich Astapenko, Valerii S. Lisitsa

Published Dec 25, 2017• 0 citations
Publisher

Abstract

We investigate the Bremsstrahlung originating from fast non-relativistic electron scattering on an atom in the spectral region near the Fano resonance including the polarization channel and interference term. It is shown that the account for polarization Bremsstrahlung leads to a significant increase of the total Bremstrahlung cross section near the Fano resonances. Numerical calculations are carried out for the first autoionization states 2l2l' of the Helium atom in the framework of the Born approximation that goes beyond the dipole approximation of the dynamic polarizability of the atom.

DOI
10.26713/jamcnp.v4i1-3.769

Related papers

Features of the bremsstrahlung accompanying collisions with a hydrogen atom in an excited state

Andrei V. Korol, O. I. Obolensky, А. В. Соловьев

The features of the bremsstrahlung appearing during a collision of a fast charged particle with a hydrogen atom (or hydrogenic ion) in an excited state are investigated. It is shown that the emission spectrum of photons with energies greater than the ionization potential of a given excited state (except the 2 s state) displays narrow lines, which are caused by de-excitation of the atom in an intermediate state. It is demonstrated that the scattering of a charged particle on an excited hydrogen atom produces a feature which is not observed in the case of scattering on a ground-state hydrogen atom. Expressions are obtained for the generalized dynamic polarizability of the hydrogen atom and hydrogenic ions in the 1 s , 2 s , and 3 s states. A method is developed for deriving expressions for the generalized dynamic polarizabilities of other excited states through the use of the Coulomb Green’s function and representation of the electronic wave function in terms of the differentiation of the generating functions of Laguerre polynomials. The bremsstrahlung cross sections for electrons and positrons colliding with hydrogen atoms in the 1 s , 2 s , and 3 s states are calculated.

Technical Physics•Oct 1, 1999•4 citations

Effects of ultrashort laser-pulse durations on Fano resonances in atomic spectra

FRANK B. ROSMEJ, Valery Alexandrovich Astapenko, Valerii S. Lisitsa

The Fano resonance theory is modified to account for photoionization by ultrashort laser pulses where the probability definition due to the nonlinear dependence on time is no longer valid. We employ the exact integrals over the Fourier transform of the photoionization cross section including the Fano resonances and a corrected Gaussian pulse shape that has vanishing electric field for zero frequency. Numerical results are presented for neutral helium that allow us to deduce the spectral distribution of the Fano resonance for different parameters and to identify the cases where the linear regime is invalid. Analytical approximations are given that provide a clear understanding of the linear and nonlinear regime related to the Fano parameter $q$, the detuned carrier frequencies, and pulse durations.

Physical Review A•Oct 31, 2014•26 citations

Two-photon laser-assisted electron scattering on hydrogen atom

A. S. Kornev, B. A. Zon

Abstract We considered the influence of light-dressed-atom effect on two-photon laser-assisted electron-atom scattering in the Born approximation. We performed calculations for the ground state of a Hydrogen atom. We demonstrated that for small scattering angles, the main contribution to the cross section is made by the combined process, when one of the photons is absorbed by the atomic electron and the second one by the scattered electron. However, in the UV region, when two-photon resonances with highly excited atomic states arise, the main contribution to the cross section is determined by the inverse polarization Bremsstrahlung absorption.

Journal of Physics B Atomic Molecular and Optical Physics•Feb 20, 2019•5 citations

Two-photon laser-assisted electron scattering on Hydrogen atom

A. S. Kornev, B. A. Zon

Synopsis We considered the influence of light-dressed-atom effect on two-photon laser-assisted electron-atom scattering in the Born approximation. We performed calculations for the ground state of a Hydrogen atom. For small scattering angles, the main contribution to the cross section is made by the combined process, when one of the photons is absorbed by the atomic electron and the second one by the scattered electron. However, in the UV region, when two-photon resonances with highly excited atomic states arise, the main contribution is determined by the inverse polarization Bremsstrahlung absorption.

Journal of Physics Conference Series•Jan 1, 2020•0 citations

Spin polarization by selective laser-induced interference

G. Alber, P. Zoller

States behaving like autoionizing states can be selectively induced by laser radiation into one of the continuum spin channels in the photoionization of polarized excited alkaki atoms. As a result of destructive or constructive interference between the direct ionization channel and those introduced by the dressing laser radiation, the cross section of this specific spin component is completely suppressed or enhanced, while leaving the other spin channel unaffected. The $q$ parameter which determines the line shape of the Fano-type resonance can be resonantly tuned as a function of the dressing laser frequency.

Physical Review A•Mar 1, 1983•17 citations

Fano interference in quantum resonances from angle-resolved elastic scattering

Prerna Paliwal, Alexander Blech, Christiane P. Koch +1 more

Asymmetric spectral line shapes are a hallmark of interference of a quasi-bound state with a continuum of states. Such line shapes are well known for multichannel systems, for example, in photoionization or Feshbach resonances in molecular scattering. On the other hand, in resonant single channel scattering, the signature of such interference may disappear due to the orthogonality of partial waves. Here, we show that probing the angular dependence of the cross section allows us to unveil asymmetric Fano profiles also in a single channel shape resonance. We observe a shift in the peak of the resonance profile in the elastic collisions between metastable helium and deuterium molecules with detection angle, in excellent agreement with theoretical predictions from full quantum scattering calculations. Using a model description for the partial wave interference, we can disentangle the resonant and background contributions and extract the relative phase responsible for the characteristic Fano-like profiles from our experimental measurements.

arXiv:2105.05959•Nature Communications•Dec 13, 2021•11 citations
We investigate the Bremsstrahlung originating from fast non-relativistic electron scattering on an atom in the spectral region near the Fano resonance including the polarization channel and interference term. It is shown that the account for polarization Bremsstrahlung leads to a significant increase of the total Bremstrahlung cross section near the Fano resonances. Numerical calculations are carried out for the first autoionization states 2l2l' of the Helium atom in the framework of the Born approximation that goes beyond the dipole approximation of the dynamic polarizability of the atom.
The features of the bremsstrahlung appearing during a collision of a fast charged particle with a hydrogen atom (or hydrogenic ion) in an excited state are investigated. It is shown that the emission spectrum of photons with energies greater than the ionization potential of a given excited state (except the 2 s state) displays narrow lines, which are caused by de-excitation of the atom in an intermediate state. It is demonstrated that the scattering of a charged particle on an excited hydrogen atom produces a feature which is not observed in the case of scattering on a ground-state hydrogen atom. Expressions are obtained for the generalized dynamic polarizability of the hydrogen atom and hydrogenic ions in the 1 s , 2 s , and 3 s states. A method is developed for deriving expressions for the generalized dynamic polarizabilities of other excited states through the use of the Coulomb Green’s function and representation of the electronic wave function in terms of the differentiation of the generating functions of Laguerre polynomials. The bremsstrahlung cross sections for electrons and positrons colliding with hydrogen atoms in the 1 s , 2 s , and 3 s states are calculated.
The Fano resonance theory is modified to account for photoionization by ultrashort laser pulses where the probability definition due to the nonlinear dependence on time is no longer valid. We employ the exact integrals over the Fourier transform of the photoionization cross section including the Fano resonances and a corrected Gaussian pulse shape that has vanishing electric field for zero frequency. Numerical results are presented for neutral helium that allow us to deduce the spectral distribution of the Fano resonance for different parameters and to identify the cases where the linear regime is invalid. Analytical approximations are given that provide a clear understanding of the linear and nonlinear regime related to the Fano parameter qqq, the detuned carrier frequencies, and pulse durations.
Abstract We considered the influence of light-dressed-atom effect on two-photon laser-assisted electron-atom scattering in the Born approximation. We performed calculations for the ground state of a Hydrogen atom. We demonstrated that for small scattering angles, the main contribution to the cross section is made by the combined process, when one of the photons is absorbed by the atomic electron and the second one by the scattered electron. However, in the UV region, when two-photon resonances with highly excited atomic states arise, the main contribution to the cross section is determined by the inverse polarization Bremsstrahlung absorption.
Synopsis We considered the influence of light-dressed-atom effect on two-photon laser-assisted electron-atom scattering in the Born approximation. We performed calculations for the ground state of a Hydrogen atom. For small scattering angles, the main contribution to the cross section is made by the combined process, when one of the photons is absorbed by the atomic electron and the second one by the scattered electron. However, in the UV region, when two-photon resonances with highly excited atomic states arise, the main contribution is determined by the inverse polarization Bremsstrahlung absorption.
States behaving like autoionizing states can be selectively induced by laser radiation into one of the continuum spin channels in the photoionization of polarized excited alkaki atoms. As a result of destructive or constructive interference between the direct ionization channel and those introduced by the dressing laser radiation, the cross section of this specific spin component is completely suppressed or enhanced, while leaving the other spin channel unaffected. The qqq parameter which determines the line shape of the Fano-type resonance can be resonantly tuned as a function of the dressing laser frequency.
Asymmetric spectral line shapes are a hallmark of interference of a quasi-bound state with a continuum of states. Such line shapes are well known for multichannel systems, for example, in photoionization or Feshbach resonances in molecular scattering. On the other hand, in resonant single channel scattering, the signature of such interference may disappear due to the orthogonality of partial waves. Here, we show that probing the angular dependence of the cross section allows us to unveil asymmetric Fano profiles also in a single channel shape resonance. We observe a shift in the peak of the resonance profile in the elastic collisions between metastable helium and deuterium molecules with detection angle, in excellent agreement with theoretical predictions from full quantum scattering calculations. Using a model description for the partial wave interference, we can disentangle the resonant and background contributions and extract the relative phase responsible for the characteristic Fano-like profiles from our experimental measurements.