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Threshold Effects In Strong-Field Ionization: Energy Shifts And Rydberg Structures, Katarzyna Krajewska, Ilya I. Fabrikant, Anthony F. Starace

Anthony F. Starace Publications

The behavior of strong-field ionization rates of neutral atoms in the vicinity ofmultiphoton ionization thresholds is analyzed using formal collision theory.Our approach,which accounts nonperturbatively for effects of an intense laser field, shows that the ionization rates have a nearly constant behavior below and above each multiphoton threshold and that between such thresholds there are an apparently finite number of rapid oscillations due to resonances with laser-field-modified Rydberg states. This pattern is typical for any atomic target, as we illustrate specifically for hydrogen and neon atoms. The flat behavior of the ionization yield near multiphoton thresholds gives the appearance of an …