EUV spectra of Rb-like to Cu-like gadolinium ions in an electron-beam ion trap

Abstract

Measurements of extreme ultraviolet radiation from highly charged gadolinium ions were made at the National Institute of Standards and Technology. The ions were produced and confined in an electron-beam ion trap (EBIT), and the spectra were recorded with a flat-field grazing-incidence spectrometer in the wavelength range 3--17 nm. Ionization stages from Rb-like to Cu-like gadolinium were selected by tuning the electron-beam energies between 0.97 and 1.7 keV. Strong intrashell $n=4$--$n=4$ transitions were identified by performing detailed collisional-radiative modeling of the EBIT plasma. A total of 73 spectral features were recorded, including 59 new identifications.