The photoelectric effect in external fields
  Atoms and negative ions interacting with laser photons yield a coherent source of photoelectrons. Applying external fields to photoelectrons gives rise to interesting and valuable interference phenomena. We analyze the spatial distribution of the photocurrent using elementary quantum methods. The photoelectric effect is shown to be an interesting example for the use of coherent particle sources in quantum mechanics. 
Christian Bracher, John B. Delos, Vassiliki Kanellopoulos, Manfred   Kleber, and Tobias Kramer