Theory of the Kapitza-Dirac effect in strong radiation fields

By applying the stationary wave functions for an electron interacting with a circularly polarized standing-wave photon field, and a nonperturbative scattering theory, we obtain a theoretical description of the Kapitza-Dirac effect in strong radiation fields. The theory predicts that large momentum transfers can occur, when two propagating light waves have the same angular momentum and opposite helicity, as observed by Bucksbaum, Schumacher, and Bashkansky as a half process in multiphoton ionization. The theory and possible experiments to detect the full Kapitza-Dirac effect in electron scattering from a strong radiation field are discussed. The theory also predicts that with the participation of ponderomotive energy, the incident electron beam, after interacting with a standing photon wave, may have symmetric reflection, asymmetric reflection, penetration, and refraction. Transition rate formulas of these processes are presented.