Spectroscopic analysis of N-intrashell transitions in Rb-like to Ni-like Yb ions.

Extreme ultraviolet spectra of highly-charged ytterbium ions produced in an electron beam ion trap at the National Institute of Standards and Technology were observed with a flat-field grazing incidence spectrometer in the wavelength region of about 4 nm-20 nm. The measured spectra were interpreted through detailed analysis by collisional-radiative modeling of the non-Maxwellian EBIT plasma. Seventy-nine new spectral lines due to intrashell (Δ = 0, = 4) electric-dipole, magnetic-dipole, and electric-quadrupole transitions were identified in Rb-like Yb through Ni-like Yb ions. The effects of strong configuration interaction within the = 4 complex on the measured spectra are discussed for a number of ionization stages.