Observation and Identification of Spectral Lines of Se-like to Fe-like Praseodymium Ions*

The spectral analysis of highly charged ions, such as highly ionized lanthanides, presents a unique opportunity to study quantum electrodynamic effects enhanced strongly by the large nuclear charges and can have significant applications in astrophysical studies. The NIST electron beam ion trap [1] was used to generate and contain charge states of Br-like Pr through Co-like Pr. Emissions in the extreme-ultraviolet (EUV) were observed using a flat-field grazing incidence spectrometer [2], and transitions were identified from the Pr ions. Electron beam energies were varied from 0.9 keV to 2.2 keV to generate the charge states of interest. The spectrometer was calibrated using well-known lines from Ne, Xe, Ar, and Ba across the wavelength range of 7.2 nm to 25.7 nm. Line identifications were made by comparing experimental and theoretical spectra generated by collisional-radiative modeling of the non-Maxwellian plasma.

[1] J. D. Gillaspy, Phys. Scr. T 71, 99 (1997).

[2] Blagojević et al., Rev. Sci. Instrum. 76, 083102 (2005).