Atomic data and spectral line intensities for S IX

✍ Scribed by A.K. Bhatia; E. Landi

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 440 KB
• Volume: 85
• Category: Article
• ISSN: 0092-640X
• DOI: 10.1016/s0092-640x(03)00057-3

✦ Synopsis

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for the O-like ion S IX. The configurations used are 2s 2 2p 4 , 2s2p 5 , 2p 6 , 2s 2 2p 3 3s, 2s 2 2p 3 3p, and 2s 2 2p 3 3d giving rise to 86 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 25, 50, 75, 100, and 125 Ry. Excitation rate coefficients are calculated by assuming a Maxwellian electron velocity distribution at several electron temperatures in the 5.6 6 log T e (K) 6 6.2 range, where S IX is formed. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8 -10 14 cm À3 . Relative spectral line intensities are calculated. Proton excitation rates among the lowest three levels have been included in the statistical equilibrium equations. The predicted S IX line intensities are compared with SUMER (SOHO) observations of the quiet Sun.