The Angular Distribution Of Ejected Electrons From Eu 4f⁷6p_1/2nd Autoionizing States

This work is devoted to the AD study of the ejected electrons from the Eu 4f76p1/2nd(n=6-9)autoionizing states with the velocity-map imaging(VMI) technique.It is well known that angular distribution(AD) of the ejected electrons from an autoionizing state is proportional to the differential cross section of the autoionization, which allows one to obtain more detailed information,compared with autoionization spectrum, representing total cross section of autoionization. Thus, study of AD may not only deepen the understanding of atomic characteristics, but also provide more experimental evidences for stringently testing the new quantum theory.Firstly, photoionization detection method is used to study the spectra of the highly excited bound states of Eu atom in the 42372-44510cm-1. Different kinds of 4f76 snl Rydberg states in this energy region are added and identified with different excitation schemes relative to other papers. Then, the combination of velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26 d autoionizing states,which are excited with different excitation scheme via the different Eu 4f76 snd 8DJ intermediate states. With the aid of selection rule for the J value, the spectra obtained with the three paths enable us to determine the unique J value for all features in the autoionization spectra. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters, are measured within the spectral profile of the 6p1/2nd autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s+ â†' 6p+. The configuration interaction is discussed with comparison of the angular distributions of ejected electrons from the different states. The present study reveals profound variations of anisotropic parameters throughout the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of 6p1/2nd autoionization series.