Effects of laser polarization in laser-assisted electron-helium inelastic collisions: a Sturmian approach

J. Phys. B: At. Mol. Opt. Phys.

Maquet

et al. 1999

Self Cite

The influence of laser polarization on the triple differential cross section (TDCS) for electron impact ionization of helium is analysed in the asymmetric coplanar geometry. The interaction of the laser field with the incident, and scattered electrons is treated non-perturbatively by using Volkov waves, while that of the ejected electron moving in the combined field of the residual ion He+ and of the laser is obtained by using the ansatz formulated by Joachain et al (1988 Phys. Rev. Lett. 61 165) for the case of atomic hydrogen. The remaining interactions are treated by using first-order perturbation theory. Detailed calculations of the scattering amplitudes are performed for a helium target. We discuss the influence of the laser polarization on TDCS as a function of the angle of ejection of the slow electron for selected choices of the laser frequency and number of photons exchanged between the external field and the electron-helium system.

Section: Discussionsupporting

confidence: 89%

Light polarization effects in laser-assisted (e,2e) collisions in helium

Makhoute

J. Phys. B: At. Mol. Opt. Phys.

Maquet

et al. 1999

Self Cite

“…where r 0 is the projectile coordinate and α 0 = E 0 /ω 2 . On the other hand, the 'dressed' wavefunctions of the atomic target in the laser field are obtained by first-order time-dependent perturbation theory, as [14] φ n (r, t) = e −iE n t e −ia•r ψ n (r)…”

mentioning

confidence: 99%

“…is the field-free second Born inelastic amplitude evaluated at the shifted momenta K i and K f . The first and second Born inelastic amplitudes corresponding, respectively, to the firstand second-order contributions to the S-matrix element for laser-assisted elastic scattering and excitation processes, have been computed exactly without further approximation with the help of a Sturmian approach, similar to that described in [10,14]. This constitutes an important advantage in the present context compared with earlier computations relying on the closure approximation [15,17].…”

mentioning

confidence: 99%

On the second Born approximation for laser-assisted electron-atom collisions

Bouzidi

Makhoute

J. Phys. B: At. Mol. Opt. Phys.

et al. 2001

Self Cite

The differential cross section for electron-hydrogen atom collisions in the presence of a CO2 laser field is analysed as a function of the incident electron energy. We show that the criticism of the second Born treatment of elastic scattering and excitation by fast electrons is unjustified for various geometrical configurations. Detailed calculations of the scattering amplitudes are performed by using the Sturmian basis expansion.

“…We present here a short description of our theoretical approach to deal with the electron's impact excitation of the helium atom in the presence of a laser field. A detailed description can be found in our previous works [32][33][34]. The scenario we considered here can be simplified into the following form:…”

Section: Theoretical Descriptionmentioning

confidence: 99%

“…where the electronic term f B 1 , elec (∆) describes the scattering of a Volkov electron by the bare atom, while the atomic amplitude term f B 1 , atom (∆) occurs as a result of the dressing effects of the atomic target by the laser field [32].…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Simultaneous Excitation of Helium by Means of an Electron and a Photon: A Joined Experimental and Theoretical Study

Ajana

Nehari

et al. 2021

Atoms

We report on a joined experimental and theoretical study of differential cross-sections resulting from inelastic scattering of a monoenergetic electron by helium atoms in the presence of an intense carbon dioxide laser. In particular, we measured the signals of the scattered electrons during the simultaneous electron–photon excitation of He 21P state for the first three microseconds of the laser pulse. The signals were measured for an incident electron energy of 45 eV and showed a structure that emerged at small scattering angles. The latter was found to be sensitive to the nature of the transferred photons, as well as the intensity of the laser field. The experimental findings were supported by quantum calculations based on the second-order Born approximation in which the correlated electron–electron interactions were taken into account.