Angular distribution of electrons elastically scattered from Ar in the presence of a 1.17 eV laser field

Experiments on free-free electron scattering by an Ar target are reported. The angular distribution of 350 eV electrons, elastically scattered at angles between 4° and 80° in the presence of 1.17 eV photons from a Nd:YAG laser, shows a pronounced maximum close to 47° and is symmetric about this angle, as predicted by a Kroll-Watson approximation calculation for the experimental kinematics. The experiments test a term in the approximation that is a strong function of the magnitude and direction of the momentum transfer of the elastically scattered electrons.