Nonresonant Above-Threshold Ionization with Circularly Polarized Sub-picosecond Pulses.
01 January 1990
Recent experiments show that above-threshold ionization (ATI) with intense linearly polarized light occurs via Stark-shifted bound-state resonances. Under identical conditions, we find that ATI with sub-picosecond circularly polarized light is non-resonant. Unlike longer-pulse experiments, these spectra directly show the ionization rate vs. intensity, and can therefore test ATI theories without deconvolving the inhomogeneous laser focus. Keldysh-Faisal-Reiss calculations do not agree with these new experimental results.