Beam-foil spectra of highly excited states in multiply charged oxygen ions

Spectra of multiply charged oxygen ions were studied in the region between 1800 and 6000 Angstrom by the beam foil method. The beam energy was 2, 4, 6 and 9 MeV for the charge state identification. Most of the intense lines a re classified as transitions between high n, l levels in O III to O VIII, w here n ranges from 9 to 15. The lines due to transitions 5l-6l' in Li-like O VI were investigated in detail in the 1800-2250 Angstrom region. Many lin es around 2070 a were attributed to the transition of the type of 1s2s5l L- 4-ls2s6l' L-4' and 1s2p5l L-4-1s2p6l' L-4', where L = l and L' = l'.