Analysis and identification of extreme-ultraviolet transitions in highly charged Nb ions

Highly charged Nb ions were produced and trapped in an electron beam ion trap at

the National Institute of Standards and Technology [1]. Emissions in the extreme-

ultraviolet (EUV) region were recorded with a flat-field grazing incidence EUV

spectrometer [2] and analyzed to identify new transitions from the Nb ions. The

electron beam energies were varied between 4.5 keV and 8.1 keV to create the

ionization level of interest. Highly charged Ne, Xe and Ba ions were used to

calibrate the EUV spectra to a wavelength region of 2-17 nm. Several new electric-

dipole and magnetic-dipole transitions from Li-like Nb 38+ to Na-like Nb 30+ were

identified by comparison with theoretical spectra created using a collisional

radiative non-Maxwellian code NOMAD.

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

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