The Formula transition array of Fe XXI and isoelectronic spectra

This detailed analysis of spectra due to $${2s}^{2}\,{2p}^{2}-\,{2s}^{2}\,{2p}\,3d $$ transitions has resulted from the application of atomic energy level calculations in which Slater parameters are adjusted so as to be consistent with established observational data. Wavelengths and energy levels are provided for elements in the isoelectronic sequence between phosphorus and iron, and oscillator strength data for magnesium to nickel. The predicted Fe XXI spectrum is related to solar flare spectra and spectra emitted from laser-produced plasmas.