The 2p(3)3s, 3p and 3d configurations of eight times ionized sulphur, S IX

The spectrum of eight times ionized sulphur, S IX, has been investigated in the wavelength region 690 to 960 Angstrom by means of the beam-foil method. Twenty-three new lines have been identified as combinations between levels of the 2p(3)3s, 3p and 3d configurations. Many of these lines have also recently been found in spectra of the solar corona recorded by the SOHO satellite. We have also identified 12 new lines between 47 and 55 Angstrom as combinations between the 2s(2)2p(4) ground configuration and 2p(3)3s and 3d. The new transitions combined with previously known data establish all 10 2p(3)3s levels, 13 of the possible 28 3p levels and 34 out of 38 3d levels. The spectroscopic identifications are supported by isoelectronic extrapolations and by theoretical calculations.