ATOMIC DATA AND SPECTRAL LINE INTENSITIES FOR Fe XI

✍ Scribed by A.K. BHATIA; G.A. DOSCHEK; W. EISSNER

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 168 KB
• Volume: 82
• Category: Article
• ISSN: 0092-640X
• DOI: 10.1006/adnd.2002.0885

✦ Synopsis

Electron impact collision strengths and spontaneous radiative decay rates are calculated for Fe XI. The data pertain to the 96 levels of the configurations 3s 2 3p 4 , 3s3p 5 , 3s 2 3p 3 3d, 3p 6 , 3s 2 3p 3 4s, and 3s 2 3p 3 4d. Collision strengths are calculated at 10 incident electron energies: 1.0, 3.4, 6.0, 12.0, 15.0, 30.0, 45.0, 60.0, 75.0, and 90.0 Ry. These atomic data are generated to support the interpretation of spectra of astrophysical objects, which frequently contain emission lines from Fe XI and similar ions. This work supplements previous work published on Fe XI by extending the calculation of collision strengths and radiative decay rates to levels within n = 4 configurations. Relative spectral line intensities are calculated for all astrophysically important transitions. These are obtained by computing the excitation rate coefficients (cm 3 s -1 ), i.e., the collision strengths integrated over a Maxwellian electron distribution, and then solving the equations of detailed balance for the populations of the 96 energy levels, assuming a collisional excitation model and an electron temperature of 1.3 × 10 6 K. This temperature is typical for Fe XI when formed at equilibrium by collisional ionization and recombination. Using the excitation rate coefficients and the radiative decay rates, level populations are computed for several electron densities. The calculation of line intensities and level populations includes proton excitation because hydrogen is the most abundant element in astrophysical plasmas relevant to Fe XI emission.