PHOTOELECTRON-SPECTROSCOPY ON ATOMIC PR AND ND IN THE 4D GIANT-RESONANCE REGION

The photoionization of atomic Pr and Nd in the region of the 4d(-1)(4, epsilon)f giant resonances has been investigated with the use of mono chromatized synchrotron radiation. The kinetic energy of the photoelec trons has been analysed, in part, with a high-resolution electron spec trometer to resolve the complex multiplet splitting. The partial cross sections for photoionization in the different electronic subshells 6s , 5p, 5s, 4f, and 4d have been determined. The character of the resona nces is found to be of highly intermediate 4d(-1)(4, epsilon)f-type, i .e. discrete and continuum transitions are almost in equilibrium. The direct 4d(-1) photoionization is discussed in terms of a tunnel model for atomic shape resonances.