Calculations of the single and multiphoton ionization of xenon valence-shell electrons are reported for several wavelengths and laser intensities. The model follows a single valence electron in the field of an effective core potential, the remaining valence electrons, frozen in their ground-state orbitals, and a linearly polarized laser field. Ionization rates and cross sections are determined using a direct numerical solution of the time-dependent Schrödinger equation using a finite-difference technique. Excellent agreement with experimental rates and previous theoretical cross sections has been obtained. Bound states, shifted into resonance by the ac Stark effect, are found to affect the ionization dynamics. Departures from perturbation theory at high intensities are demonstrated and discussed.

• Received 25 January 1988

DOI:https://doi.org/10.1103/PhysRevA.38.778