THE 2P(3)3S, 3P AND 3D CONFIGURATIONS OF 8 TIMES IONIZED SULFUR, S-IX

The spectrum of eight times ionized sulphur, S IX, has been investigat ed in the wavelength region 690 to 960 Angstrom by means of the beam-f oil method. Twenty-three new lines have been identified as combination s between levels of the 2p(3)3s, 3p and 3d configurations. Many of the se lines have also recently been found in spectra of the solar corona recorded by the SOHO satellite. We have also identified 12 new lines b etween 47 and 55 Angstrom as combinations between the 2s(2)2p(4) groun d 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 possi ble 28 3p levels and 34 out of 38 3d levels. The spectroscopic identif ications are supported by isoelectronic extrapolations and by theoreti cal calculations.