Electron Collision Excitation of Fine‐Structure Levels in Siv

Electron collision excitation strengths of inelastic transitions among the 52 fine-structure levels of the ground 3 s 2 3 p and excited 3 s 3 p 2 , 3 s 2 3 d , 3 s 2 4 s , 3 p 3 , 3 s 2 4 p , 3 s 3 p 3 d , 3 s 2 4 d , 3 s 2 4 f , and 3 s 3 p 4 s configurations in S IV are calculated using full Breit-Pauli R -matrix method. The target levels are represented by configuration-interaction wave functions, and the mass, Darwin, and spin-orbit relativistic terms are included in the scattering equations. The collision strengths in the threshold energy regions are dominated by the complicated resonance structures. Our collision strengths are compared with earlier available calculations and significant differences are noted. The collision strengths are integrated over a Maxwellian distribution of electron energies to obtain effective collision strengths over a wide temperature range.