Extended analysis of the spectrum of seven-times ionized yttrium (Y VIII)

Abstract

The spectrum of seven-times ionized yttrium, Y VIII, was photographed with a sliding-spark discharge and a 10.7-m grazing-incidence spectrograph. The region of observation was 219–589 Å. Previous results for the 4s24p2 ground configuration and excited configurations 4s4p3 and 4s24p5s were confirmed. Previous results for the 4s24p4d configuration were partially confirmed. New levels were found for the 4s24p4d and 4p4 configurations, bringing the total analysis to 70 lines and 32 energy levels. The observed configurations were interpreted with Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels. Transition probabilities for the observed lines were calculated with the fitted parameters. By using the observed 4s24p5s energy levels and a semi-empirical value for the effective quantum number n*(4s24p5s), a new value was determined for the ionization energy: 1,033,340 ± 1000 cm−1 (128.12 ± 0.12 eV).