Angular Distribution of Photoelectrons in Strongly Driven Multiphoton Transitions

Abstract
The behavior of photoelectron angular distributions in a strongly driven resonant multiphoton ionization process is discussed. It is shown that the angular distribution changes drastically with increasing intensity as a result of the ac Stark shifting of the levels. Moreover, under strong saturation conditions the distribution reaches a limiting form significantly different from the form predicted by perturbation theory. The effects of the laser bandwidth on the angular distribution are also discussed briefly.