CALCULATION OF PARTIAL PHOTOION-YIELD SPECTRA FOR ND, EU, GD AND DY

Photoion-yield spectra for Nd, Eu, Gd and Dy have been calculated taki ng into account the cascade of Auger and shake-off processes following photoionization of 4d, 4f, 5s and 5p shells. Global characteristics o f Auger spectra as well as of transition zones are used to describe tr ansitions between complex configurations. For all investigated element s a qualitative agreement with experimental spectra is obtained. The p redominance of Nd3+ ions is mainly caused by the Auger decay of 4d(-1) vacancy and shake-off processes. The production of abundant Euf ions is determined by the selective population of low Eu+ 4f(-1) states for which the Auger decay is forbidden energetically. In Gd the significa nt part of such states become autoionizing states and it results in th e majority of Gd2+ ions. The dominating Dy+ signal is explained by the effective population of states with a 4f(-1) vacancy through the dire ct photoionization and Auger decay of the excited 4d(9)4f(11) configur ation.