Collision Strengths for Electron Impact Excitation of Fine‐Structure Levels in Fexiii

Abstract

Electron collisional excitation strengths for transitions among the fine-structure levels of the ground 3s23p2 configuration and from the levels of 3s23p2 configuration to the levels of the excited 3s3p3 and 3s23p3d configurations in Fe XIII are calculated using a semirelativistic R-matrix approach. We considered 14 LS 3s23p23P,1D,1S, 3s3p33Do,3Po,1Do,3So,1Po, 3s23p3d3Po,1Do,3Do,3Fo,1Fo, and 1Po states of Fe XIII in the present calculation. The 14 LS states give rise to 26 fine-structure levels that are represented by configuration-interaction wave functions. The relativistic effects are included in the Breit-Pauli approximation via one-body mass correction, Darwin, and spin-orbit interaction terms in the scattering equations. Complicated resonance structures are explicitly included in the collision strengths. The collision strengths are integrated over a Maxwellian distribution of electron energies to give effective collision strengths over a wide temperature range from 5 × 105 to 5 × 106 K.