Using a grazing-incidence spectrometer and a low-inductance 14-µF, 12–15-kV spark source, we have observed spectra of Mg X, Al XI, and Si XII. About 50 new lines are reported between 25 and 65 Å, arising from transitions between the lowest 2s and 2p configurations and ns, np, and nd configurations, where n≥3.
URI FELDMAN, LEONARD COHEN, and WILLIAM BEHRING, "Lithium-Like Spectra in Mg, Al, and Si," J. Opt. Soc. Am. 60, 891-893 (1970)