The C IV, N V, O VI and F VII quartet term systems have been investigated using the beam-foil method, Wavelengths of more than 70 lines associated with these systems are reported. They are compared to theoretical predictions and to data on analogous transitions in singly excited four-electron ions.Certain details of the term structure are discussed as are fine structure splittings and the separations of quartet terms arising from electron configuration 1s2p3p, 1s2p3d, and 1s2p4d. In the isoelectronic comparison the effect of configuration mixing becomes apparent for the last case.

Using the method of beam-foil spectroscopy we have measured the decay times of several n = 3 terms in Mg-like Ni XVII. By applying an effective method for correction of cascades (ANDC) we obtained reliable lifetimes for the terms 3s3p1P, 3s3p3P, 3p2 1D and 3p2 3P. The experimental data are in good agreement with recent theoretically predicted values.

In the emission spectra of beam-foil excited oxygen and fluorine, it has been possible to assign lines to the quartet term systems of doubly excited three electron ions. A comparison with known spectra of singly excited four-electron systems turned out to be useful for line identification. The measured wavelengths are compared to theoretical predictions.

The spectrum of Ti XIV has been observed in the wavelength region 80-5508 using the fast ion beam spectroscopy method. 47 lines have been identified as transitions between the 2p4 3s, 3p, and 3d configurations in the 360-5408 interval. The level identifications are supported by comparisons between observations and Hartree-Fock calculations along the F I isoelectronic sequence.

The EUV spectrum of lithium in the wavelength range 10-28nm has been recorded with high spectral resolution. About one hundred lines of Li 111, singly and doubly excited Li I1 and doubly excited Li I have been identified. The line-rich spectrum obtained after foil excitation is contrasted with the spectrum obtained after He gas excitation of Li' ions. The lifetimes of three core-excited states have been determined and found to agree with theoretical predictions.