Electron--Helium Scattering in Free--Free Transitions in a Bichromatic Laser Field

Theoretical calculation of the differential cross section (DCS) for elastic electron--helium scattering in the presence of a bichromatic CO₂ laser field is carried out in the first Born approximation with a simple screening electric potential. The two components of the laser field have the frequencies ω and 2ω, which are out of phase by an arbitrary scale vp. The variations of the differential cross section as a function of the phase angle vp in the domain
0°≤ψ≤ 360°are presented. We discuss the influence of the number of photons exchanged on the phase-dependence effect. Moreover, for different scattering angles and incident electron energies, the DCS has outstanding differences. These illustrate that the two parameters have important effects on the differential cross section and the screening electric potential is effective.