Collision Strengths For [O II] and [S II]

Collision strengths and parameters $$\Upsilon (i\rightarrow j)$$ required for the calculation of collisional rate coefficients are calculated for the fine-structure transitions $${2D}_{3/2}-{2D}_{5/2},{2P}_{1/2}-{2P}_{3/2},\,{4S}_{3/2}-{2D}_{J},\,{4S}_{3/2}-{2P}_{J}\,\text{and}\,{2D}_{J}-{2P}_{J^\prime}$$ within the ground configuration of [O II]. The complicated resonance structure in the $${2D}_{3/2}-{2D}_{5/2} $$ collision strength above the 2D threshold is taken into account. The collision strengths are obtained from reactance matrices calculated by Pradhan using the close-coupling approximation. Distorted-wave and close-coupling calculations are made for the forbidden transitions in the ground configuration of [S II]. The target is represented by the ground configuration, 3s²3p³, plus the quasi-degenerate configuration 3p⁵, which gives some correlation effect. The present close-coupling results confirm the essentially similar calculation of Conneely, Smith & Lipsky, and the present distorted-wave results are in good agreement with the closecoupling results but are not in agreement with the earlier distorted wave calculations of Czyzak & Krueger.