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 pr oduced by the beam-foil technique have been analysed in the 5-40 nm wa velength 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 first time. The assignment of spectral lines was corroborated by comparison along the isoelectronic sequence .