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

Physical Review A

Calculation of free-free radiative absorption cross sections

Philip W. Coulter

Published Nov 1, 1983• 11 citations
Publisher

Abstract

One-photon free-free absorption cross sections are evaluated by means of an integral relationship involving electron-atom off-shell scattering amplitudes. Off-shell effects are explicitly calculated and compared to various on-shell approximations. This calculation shows that off-shell effects become small with increasing energy as expected. One of the on-shell approximations agrees with the exact result over the entire energy range under consideration to within a few percent. The only integrals which appear in the calculations are absolutely convergent in contrast to methods used in previous calculations.

DOI
10.1103/physreva.28.2881

Related papers

One- and two-photon ionization of model atoms: The sphericalδ-shell potential

Giovanni P. Arrighini, Carla Guidotti, N. Durante

One- and two-photon ionization cross sections for the negative hydrogen ion ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ are evaluated by using a one-electron model where the effective intra-atomic potential energy is assumed to be of a very-short-range character and approximated by a ``spherical \ensuremath{\delta} shell.'' The adjustment of the two parameters involved in the model potential so as to reproduce either the photodetachment energy or the behavior of the one-photon ionization cross section over a substantial range of frequencies beyond the ionization threshold leads to conjecture of a reasonable estimate of the two-photon ionization cross section over the proper range of frequencies of the ionizing field.

Physical Review A•Feb 1, 1987•18 citations

Electron scattering from atoms in the presence of a laser field. III

Marvin H. Mittleman

The development of the theory of the effect of a laser on electron-atom scattering is continued by the derivation of explicit relations between the observed electron-atom scattering cross sections in the presence of a laser and exact electron-atom scattering cross sections with no laser present. No approximation concerning the scattering interaction is made. The only approximations concerning the laser are that (1) the laser-atom interaction energy is small compared to atomic energies, (2) the Rabi frequency times the collision time is small, and (3) the laser intensity in appropriate units is small.

Physical Review A•Oct 1, 1977•21 citations

SINGLE PHOTON FREE-FREE TRANSITIONS

K L Bell

A brief review of single photon free-free transitions, in which a photon is absorbed by an electron in the presence of an atom, is presented.

Journal de Physique IV (Proceedings)•Mar 1, 1991•0 citations

Free-free experiments: dressed-atom effects during inelastic electron scattering

Nicholas L S Martin, B N Kim, C.M. Weaver +1 more

Synopsis Experiments and theory will be presented for the emission/absorption of 1.17 eV photons by electrons during the electron-impact excitation of a helium target in a laser field.

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

Theoretical model for the collision of high Rydberg atoms with neutral atoms or molecules

E. de Prunelé, J. Pascale

A theoretical model for the collision of atoms in high Rydberg states (nl) with neutral atoms or molecules is proposed, based on the assumption that the electron-perturber interaction is of very short range compared with the mean radius of the Rydberg atom. A semiclassical method is used to derive a compact expression for the collision probability. The calculations need total cross sections for the scattering of a free and low-energy electron by the perturber. The model is applied to the calculation of a free and low-energy electron by the perturber. The model is applied to the calculation of cross sections for the quenching of n 2 D or n 2 F Rydberg states of Na and Rb by rare-gas atoms of N 2 . On the whole the calculated cross sections are in reasonable agreement with experimental data for n>10 approximately. The model and the results of the calculations are discussed and compared with other theoretical works.

Journal of Physics B Atomic and Molecular Physics•Aug 14, 1979•77 citations

Positronium scattering by atomic hydrogen with inclusion of target excitation channels

Jennifer E Blackwood, Mary T. McAlinden, H. R. J. Walters

Calculations are reported for positronium (Ps) scattering by atomic hydrogen (H) in the energy range 0--6.5 eV in a coupled-pseudostate approximation in which excitation and ionization channels of both the Ps and the H are taken into account. The approximation contains an accurate representation of the van der Waals coefficient. Results are presented for phase shifts, scattering lengths, effective ranges, and various cross sections including partial wave, total, and ortho-para conversion cross sections. An analysis of the possible spin transitions is provided and the energy of the positronium hydride (PsH) bound state is determined. Substantial differences are found from earlier work within the frozen target approximation, now clearly confirming the importance of target excitation channels. Good agreement is obtained with recent calculations of S-wave phase shifts and scattering lengths using the stabilization method. Convergence to the exact binding energy for PsH appears to be slow. Resonances corresponding to unstable states of the positron orbiting ${\mathrm{H}}^{\ensuremath{-}}$ are seen in the electronic spin singlet partial waves. The importance of the ${\mathrm{H}}^{\ensuremath{-}}$ formation channel is discussed.

Physical Review A•Feb 27, 2002•52 citations
One-photon free-free absorption cross sections are evaluated by means of an integral relationship involving electron-atom off-shell scattering amplitudes. Off-shell effects are explicitly calculated and compared to various on-shell approximations. This calculation shows that off-shell effects become small with increasing energy as expected. One of the on-shell approximations agrees with the exact result over the entire energy range under consideration to within a few percent. The only integrals which appear in the calculations are absolutely convergent in contrast to methods used in previous calculations.
One- and two-photon ionization cross sections for the negative hydrogen ion ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ are evaluated by using a one-electron model where the effective intra-atomic potential energy is assumed to be of a very-short-range character and approximated by a ``spherical \ensuremath{\delta} shell.'' The adjustment of the two parameters involved in the model potential so as to reproduce either the photodetachment energy or the behavior of the one-photon ionization cross section over a substantial range of frequencies beyond the ionization threshold leads to conjecture of a reasonable estimate of the two-photon ionization cross section over the proper range of frequencies of the ionizing field.
The development of the theory of the effect of a laser on electron-atom scattering is continued by the derivation of explicit relations between the observed electron-atom scattering cross sections in the presence of a laser and exact electron-atom scattering cross sections with no laser present. No approximation concerning the scattering interaction is made. The only approximations concerning the laser are that (1) the laser-atom interaction energy is small compared to atomic energies, (2) the Rabi frequency times the collision time is small, and (3) the laser intensity in appropriate units is small.
A theoretical model for the collision of atoms in high Rydberg states (nl) with neutral atoms or molecules is proposed, based on the assumption that the electron-perturber interaction is of very short range compared with the mean radius of the Rydberg atom. A semiclassical method is used to derive a compact expression for the collision probability. The calculations need total cross sections for the scattering of a free and low-energy electron by the perturber. The model is applied to the calculation of a free and low-energy electron by the perturber. The model is applied to the calculation of cross sections for the quenching of n 2 D or n 2 F Rydberg states of Na and Rb by rare-gas atoms of N 2 . On the whole the calculated cross sections are in reasonable agreement with experimental data for n>10 approximately. The model and the results of the calculations are discussed and compared with other theoretical works.
Calculations are reported for positronium (Ps) scattering by atomic hydrogen (H) in the energy range 0--6.5 eV in a coupled-pseudostate approximation in which excitation and ionization channels of both the Ps and the H are taken into account. The approximation contains an accurate representation of the van der Waals coefficient. Results are presented for phase shifts, scattering lengths, effective ranges, and various cross sections including partial wave, total, and ortho-para conversion cross sections. An analysis of the possible spin transitions is provided and the energy of the positronium hydride (PsH) bound state is determined. Substantial differences are found from earlier work within the frozen target approximation, now clearly confirming the importance of target excitation channels. Good agreement is obtained with recent calculations of S-wave phase shifts and scattering lengths using the stabilization method. Convergence to the exact binding energy for PsH appears to be slow. Resonances corresponding to unstable states of the positron orbiting ${\mathrm{H}}^{\ensuremath{-}}$ are seen in the electronic spin singlet partial waves. The importance of the ${\mathrm{H}}^{\ensuremath{-}}$ formation channel is discussed.