The Spectrum and Term System of S VII

Abstract

The spectrum of six times ionized sulphur, S VII, has been investigated in the wavelength region 200–4000 Å by means of the beam-foil and laser-produced plasma techniques. The analysis comprises 219 lines of which 105 are newly identified. The present work establishes 123 2s22p5 nl energy levels of which 66 are new. The level energies are determined with an internal consistency of better than 20 cm-1. The observed level structure has been investigated by means of parametric calculations. The center-of-gravity ionization energy of the 2s22p5 2P limit has been determined to 2 269 410±60 cm-1. Of the identified 3s-3p and 3p-3d lines 27 are present in the solar coronal spectrum recorded by the SUMER instrument onboard the SOHO satellite. The present work adds 2 new solar identifications and improved wavelengths of some other solar coronal lines.