Electron Collision Rates for Ultraviolet and X‐Ray Lines of S x

Abstract

Electron collisional excitation strengths and rates for ultraviolet and X-ray lines arising from transitions between the fine-structure levels of the 2s22p3 4So, 2Do, and 2Po terms and from these levels to the levels of the 2s2p4, 2p5, 2s22p23s, 2s22p23p, and 2s22p23d configurations have been calculated using Breit-Pauli R-matrix method. Configuration-interaction wave functions have been used for an accurate representation of target levels. These wave functions give excitation energies and oscillator strengths which are in close agreement with experiment and other accurate calculations. The Rydberg series of resonances converging to the n = 2 and n = 3 excited levels are explicitly included in the scattering calculation. Resonance structures make significant contribution to collision strengths. The effective collision strengths are obtained by integrating total collision strengths over a Maxwellian distribution of electron energies, and these are presented over a wide temperature range suitable for modeling of astrophysical plasmas. Significant differences with earlier results of effective collision strengths are noted.