A classical and semiclassical study of electron-atom collisions in the presence of mono- and bichromatic low-frequency laser fields

Laser-assisted electron-atom collisions are studied using classical mechanics and short- and long-ranged model potentials for the electron-atom interaction. The classical energy transfer is compared with the values predicted by the soft-photon approximation and the differences are related to an adiabaticity parameter, which indicates the ratio of the time scales involved. Radiation of arbitrary polarization and the case of the combination of a laser fundamental and its first or second harmonic are also considered.