Beam-foil spectroscopy in the extreme UV of highly ionized silicon Si XI and the isoelectronic ions Al X, S XIII and Ar XV

Spectra of highly-ionized silicon, aluminium, sulfur and argon ions produced by the beam-foil technique have been analysed in the 5-40 nm wavelength range. Numerous transitions belonging to n = 3-4, 4-5 and 3-5 transitions arrays in the beryllium-like spectra Al X, Si XI, S XIII and Ar XV were observed for the fist time. The assignment of spectral lines was corroborated by comparison along the isoelectronic sequence. (orig.)