Low-energy electron-helium scattering in a Nd-YAG laser field

We study the electron-impact excitation of atomic helium, in the presence of a linearly polarized Nd-YAG laser field, accompanied by the transfer of ℓ photons, for low collision energy of 25 eV and laser intensity of 5.3 × 1011 W cm−2. The second-order Born approximation has been used to calculate the differential cross sections. Detailed calculations of the scattering amplitudes are performed by using the Sturmian basis expansion. A detailed analysis is made of the excitation of the 11S → 21S and 11S → 21P transitions. We discuss the behavior and the variation of the cross sections corresponding to the excitation process for various geometrical configurations.