Experiments on multiphoton free-free transitions

Multiphoton free-free transitions are detected in the scattering of electrons on argon atoms and on hydrogen molecules in the presence of an intense pulsed C${\mathrm{O}}_2$ laser field. The authors present measurements for several values of the incoming electron energy, the electron scattering angle, and the angle between the laser polarization vector and the electron momentum transfer. All observations are in qualitative agreement with a recent theoretical model based on a low-frequency approximation.