Photoionization cross sections of doubly excited resonances in ytterbium

Abstract

The authors report measurements of doubly excited resonances in the ground-state photoionization spectrum of ytterbium using the monochromatized synchrotron radiation from the DORIS II storage ring at HASYLAB and a thermionic diode detector. Their measurements cover the J=1' spectrum between 48000 and 80000 cm-1. It was possible to observe the doubly excited resonances at a much improved signal-to-noise ratio and the error in the cross section is estimated to be about 10%. The photoionization cross section is dominated by strongly autoionizing resonances which are interpreted as members of the doubly excited Rydberg series built on the 4f 14 5d (2D32/, 5/2) and 4f 14 6p(2P1/2, 3/2) parent ion configurations. Lifetimes, shape parameters and resonance energies of the broad overlapping resonances which belong to the (Xe)4f 14 5d6p configuration were extracted from the photoionization cross sections using a relation derived by Mies (1968).