Breakdown of the three-parameter model for the dichroism in the 4f photoelectron spectrum of laser-aligned Eu atoms

The dichroism in the 4f photoelectron spectra of laser-aligned Eu atoms has been determined with linearly polarized vacuum ultraviolet radiation. The experimental results disagree with the prediction of the three-parameter mo del based on the absolute magnitude and relative phase of the 4f --> epsilo n d, epsilon g transition matrix elements. It is suggested that strong conf iguration interactions, confirmed in high-resolution photoelectron spectra, are the cause of the breakdown of the three-parameter model.