Influence of Configuration Mixing in Intermediate States on Resonant Multiphoton Ionization

Abstract
Resonant three-photon ionization of Ba to a structureless continuum via 6snd Rydberg states was performed in the range 19<~n<~30. It is shown that state mixing in the Rydberg states strongly affects the photoion and photoelectron yields as well as the angular distributions of photoelectrons. The experimental results are explained on the basis of a three-channel quantum-defect theory for the perturbed Rydberg series.