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 Physics B Atomic and Molecular Physics

Scattering of electrons by hydrogen atoms in a laser field

R S Pundir, K. C. Mathur

Published Jul 14, 1982• 4 citations
Publisher

Abstract

The perturbation approach, based on the space translation approximation (STA), to treating the bound states of atomic hydrogen in the presence of a laser field is analysed. It is shown that the first-order approximation, STA1, is unsuitable and does not modify the bound states of the hydrogen atom in the presence of the field. The authors derive the second-order approximation, STA2, which leads to changes in the bound-state spectrum.

DOI
10.1088/0022-3700/15/13/010

Related papers

Coherent phase control in electron scattering by hydrogen atoms in a bichromatic laser field

Aurelia Cionga, F. Ehlotzky, Gabriela Buică

We consider electron scattering by hydrogen atoms in a bichromatic linearly polarized laser field of frequencies ω and 3ω and we discuss the coherent control of the scattering process as a function of the relative phase φ between the two components of the radiation field. The electrons are assumed to have sufficiently high energies in order to permit the description of the scattering process in the first-order Born approximation. The scattered electrons, embedded in the bichromatic laser field of moderate power, as well as the laser dressing of the hydrogen atoms in their ground state are described by time-dependent perturbation theory. We discuss the angular dependence of the nonlinear differential scattering cross sections for the low values N = ±2 of absorbed or emitted laser photons as a function of the relative phase φ between the two radiation field components. We also compare our results with those obtained from the assumption of a static potential describing the target atom.

Journal of Physics B Atomic Molecular and Optical Physics•May 4, 2001•9 citations

Elastic scattering of electrons by metastable hydrogen atoms in the presence of a resonant laser field

S. P. Purohit, Anoop K. Jain, K. C. Mathur

Within the framework of the rotating wave approximation the elastic scattering of electrons by metastable 2s state of hydrogen atoms is studied in the presence of a resonant laser field. The frequency of the circularly polarized laser field is chosen to match the 2s-3p transition frequency in the hydrogen atom. Variation of the cross section with laser intensity and with incident electron energy (50-150 eV) is investigated.

The European Physical Journal D•Jan 1, 1998•4 citations

Electron-atom scattering in a resonant laser field

K. Unnikrishnan

Dressed states of an atom in a classical laser field of frequency close to an atomic transition frequency are obtained, which are a considerable improvement over the usual two-level rotating-wave approximation. These wave functions are used in a calculation of the cross section for elastic electron-atom scattering in a laser field. Numerical calculations for electron-hydrogen scattering demonstrate that scattering involving absorption or emission of photons can be strongly influenced by coupling to the nonresonant states, regardless of the field strength. Inclusion of the counter-rotating terms in the calculation is shown to be essential for extending the applicability of the theory to scattering in nonresonant fields, where a first-order perturbation-theoretic treatment of the atom-field interaction would be expected to be quite justified.

Physical Review A•Sep 1, 1988•15 citations

Bound states of atomic hydrogen in a laser field beyond the nonrelativistic dipole approximation

Predrag Krstić, Marvin H. Mittleman

Recent calculations on the bound states of atomic hydrogen in a laser field in the nonrelativistic dipole approximation have produced metastable states with decreasing binding energy as a function of ${\mathrm{\ensuremath{\alpha}}}_{0}$\ensuremath{\sim}${\mathit{I}}^{1/2}$${\mathrm{\ensuremath{\omega}}}^{\mathrm{\ensuremath{-}}2}$ (where I is the laser intensity and \ensuremath{\omega} is its frequency). We extend the calculations by removing these restrictions. We find the limit of validity of the previous calculations and find that beyond this limit of ${\mathrm{\ensuremath{\alpha}}}_{0}$ the lowest bound state persists but that its character is completely changed.

Physical Review A•Oct 1, 1990•26 citations

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

Marvin H. Mittleman

In the first paper of this series a formal theory of atomic scattering of electrons in the presence of an intense electromagnetic field was given. Cross sections, near the forward direction, between atomic states (modified by the laser) were obtained. However, it was assumed that the atom could not emit spontaneous radiation. In this paper the effect of spontaneous radiation is included, and it is shown that in most cases the measured cross section will be a weighted average of the two different cross sections starting from the two different initial states which are those atomic states resonantly linked by the laser. The Born approximation for the scattering is obtained, and it is shown that for the simplest description of the spontaneous radiation field the effect of the laser on the cross sections is simply to multiply them by a factor which depends upon the laser detuning.

Physical Review A•Oct 1, 1976•38 citations

Photoelectric effect in the presence of a bichromatic laser field

Liang Bai, Wen-Yuan Du, Shu-Min Li +1 more

Photoelectric effect in atomic hydrogen in the presence of bichromatic laser fields composed of a fundamental frequency and its second or third harmonics is investigated. The expression of the S-matrix for the laser-assisted photoelectric effect is derived in the length gauge, which can simplify the elements of the matrix. A general dressed wavefunction of the atom is derived in perturbation theory. The continuum state of the ejected electron is described by a Coulomb–Volkov wavefunction. Numerical results of photoionization cross section for the distinct second component are obtained and compared with the monochromatic field dressing case. It is shown that the photoionization cross section is modified notably by introducing the second component of field, especially when the colliding system absorbs or emits a considerable number of laser photons.

Journal of Physics B Atomic Molecular and Optical Physics•Oct 29, 2010•0 citations
The perturbation approach, based on the space translation approximation (STA), to treating the bound states of atomic hydrogen in the presence of a laser field is analysed. It is shown that the first-order approximation, STA1, is unsuitable and does not modify the bound states of the hydrogen atom in the presence of the field. The authors derive the second-order approximation, STA2, which leads to changes in the bound-state spectrum.
We consider electron scattering by hydrogen atoms in a bichromatic linearly polarized laser field of frequencies ω and 3ω and we discuss the coherent control of the scattering process as a function of the relative phase φ between the two components of the radiation field. The electrons are assumed to have sufficiently high energies in order to permit the description of the scattering process in the first-order Born approximation. The scattered electrons, embedded in the bichromatic laser field of moderate power, as well as the laser dressing of the hydrogen atoms in their ground state are described by time-dependent perturbation theory. We discuss the angular dependence of the nonlinear differential scattering cross sections for the low values N = ±2 of absorbed or emitted laser photons as a function of the relative phase φ between the two radiation field components. We also compare our results with those obtained from the assumption of a static potential describing the target atom.
Dressed states of an atom in a classical laser field of frequency close to an atomic transition frequency are obtained, which are a considerable improvement over the usual two-level rotating-wave approximation. These wave functions are used in a calculation of the cross section for elastic electron-atom scattering in a laser field. Numerical calculations for electron-hydrogen scattering demonstrate that scattering involving absorption or emission of photons can be strongly influenced by coupling to the nonresonant states, regardless of the field strength. Inclusion of the counter-rotating terms in the calculation is shown to be essential for extending the applicability of the theory to scattering in nonresonant fields, where a first-order perturbation-theoretic treatment of the atom-field interaction would be expected to be quite justified.
Recent calculations on the bound states of atomic hydrogen in a laser field in the nonrelativistic dipole approximation have produced metastable states with decreasing binding energy as a function of ${\mathrm{\ensuremath{\alpha}}}_{0}$\ensuremath{\sim}I1/2{\mathit{I}}^{1/2}I1/2${\mathrm{\ensuremath{\omega}}}^{\mathrm{\ensuremath{-}}2}$ (where I is the laser intensity and \ensuremath{\omega} is its frequency). We extend the calculations by removing these restrictions. We find the limit of validity of the previous calculations and find that beyond this limit of ${\mathrm{\ensuremath{\alpha}}}_{0}$ the lowest bound state persists but that its character is completely changed.
In the first paper of this series a formal theory of atomic scattering of electrons in the presence of an intense electromagnetic field was given. Cross sections, near the forward direction, between atomic states (modified by the laser) were obtained. However, it was assumed that the atom could not emit spontaneous radiation. In this paper the effect of spontaneous radiation is included, and it is shown that in most cases the measured cross section will be a weighted average of the two different cross sections starting from the two different initial states which are those atomic states resonantly linked by the laser. The Born approximation for the scattering is obtained, and it is shown that for the simplest description of the spontaneous radiation field the effect of the laser on the cross sections is simply to multiply them by a factor which depends upon the laser detuning.
Photoelectric effect in atomic hydrogen in the presence of bichromatic laser fields composed of a fundamental frequency and its second or third harmonics is investigated. The expression of the S-matrix for the laser-assisted photoelectric effect is derived in the length gauge, which can simplify the elements of the matrix. A general dressed wavefunction of the atom is derived in perturbation theory. The continuum state of the ejected electron is described by a Coulomb–Volkov wavefunction. Numerical results of photoionization cross section for the distinct second component are obtained and compared with the monochromatic field dressing case. It is shown that the photoionization cross section is modified notably by introducing the second component of field, especially when the colliding system absorbs or emits a considerable number of laser photons.