Angular distribution of photoelectrons in the above-threshold ionization of atomic hydrogen

Abstract
Using a multichannel version of the quantum-optical model of above-threshold ionization, we compute the angular distribution of photoelectrons for atomic hydrogen irradiated by a powerful linearly polarized laser pulse. We take into account the distortion of atomic continua by the presence of the strong laser. The distributions are peaked along the polarization direction. The results are in striking but qualitative agreement with the recent experiment of D. Feldmann et al. [Z. Phys. 6, 293 (1987)] for six- and four-photon ionization of hydrogen.