Stimulated Compton Backscattering and the High Intensity Kapitza-Dirac Effect*

Abstract

We report the scattering of low energy free electrons from an optical standing wave at intensities of 1013 to 1014W/cm2.1 This interaction is the high intensity limit of the Kapitza-Dirac effect,2 wherein electrons Bragg scatter from the standing wave "lattice". In this regime, the momentum exchanged exceeds the reciprocal lattice vector by a factor of 500 or more, and the scattering rate is compar able to the optical frequency. The electron motion is most easily analyzed by classical mechanics.