STABILIZATION IN RELATIVISTIC PHOTOIONIZATION WITH CIRCULARLY-POLARIZED LIGHT

Relativistic ionization rates and related phenomena are calculated for ground-state hydrogen atoms in the presence of a circularly polarized electromagnetic field. A Dirac formalism is used, with spin effects fully included. A primary purpose of this work is to explore the effects of relativity on atomic strong-field stabilization. A wide range of frequencies is covered, and in all cases relativistic effects first dampen the stabilization phenomenon as the field intensity increases, and then strongly enhance it in the intensity domain where the ponderomotive potential exceeds the electron rest energy. Relativistic effects can produce major changes in the photoelectron energy spectrum, but perhaps the most easily observable effect is the major shift that can occur in the photoelectron angular distribution.