Effects of a laser field on electron-atom ionizing collisions

The presence of a laser field is found to alter significantly the shape of the angular distribution of ejected electrons in electron-atom ionizing collisions when photon exchanges occur. Laser electric fields parallel to the primary electron transferred momentum (→EL∥→Kif) increase the number of secondary electrons ejected in the backward direction (with respect to →Kif). Laser electric fields perpendicular to →Kif double the peaks present in the field-free angular distribution and rotate them symmetrically in opposite directions from the →Kif axis towards the →EL axis. Calculations are presented for ionization events accompanied by one-photon absorption in a coplanar asymmetric geometry.