Electron-helium scattering in a Nd-YAG Laser field at collision energies near the He(1s2l) thresholds

The R-matrix Floquet method is used to study electron-helium scattering in a Nd-YAG laser in the energy range from 0.65 to 0.78 Hartree. The effect of strong AC Stark mixing between the 1s2s S-3 and 1s2p P-3(o) states is discussed. Integrated cross sections for elastic scattering and excitation from the ground state into the triplet states are presented. The He-(1s2s(2) S-2) resonance is shown to be a dominant feature below the field-free threshold.