Photoion yield spectra of singly and doubly charged lanthanides in the region of the 5pexcitation: The elements La, Ce, Pr, Nd, Sm, and Eu

Using synchrotron radiation, an atomic beam technique, and a time-of-flight spectrometer the photoion yield spectra of the singly and doubly charged lanthanides La, Ce, Pr, Nd, Sm, and Eu in the region of the 5p excitation between 20 and 40 eV were measured. The experimental results are discussed within the concept of autoionizing atomic states and the production of doubly charged photoions by stepwise processes. For Pr, as an example, the partial cross sections of the subshells 6s1/2, 4f5/2, 5p3/2, and 5p1/2 were calculated with the method of the time-dependent local-density approximation, and the results are compared with the Pr⁺ and Pr²⁺ signals.