Photoelectron studies of the4fand6ssubshells in atomic ytterbium

The dynamic properties of the 4f subshell in atomic ytterbium were studied experimentally with the aid of synchrotron radiation and theoretically in the relativistic random-phase approximation (RRPA). Satisfactory agreement between experiment and theory was obtained for the β parameter, the R(4$f_{7/2}$/4$f_{5/2}$) branching ratio and the relative partial cross sections between 17.5 and 100 eV. This indicates that 4f photoionization is described well in the RRPA model. The properties of the 6s subshell were measured between 17.5 and 50 eV. In the resonance region 5p→5d the population of the three main exit channels 6s, 4$f_{7/2}$, and 4$f_{5/2}$ were recorded in detail between 24 and 31 eV using the constant-ionic-state technique. For the approximately 15 resonance states similar populations of all channels were found. The 5p resonance structure was also calculated using a limited number of interacting channels in the multichannel quantum-defect theory.