Fine-structure transitions by electron impact in singly-ionized sulphur

Reaction-rate parameters $$\Upsilon(j\rightarrow i)$$ are obtained for the fine-structure transitions within the ground configuration of S II. In particular the astronomically important $$^2D^0_{3/2}-^2D^0_{5/2}$$ collision strength is considered, taking into account the detailed resonance structure just above threshold. The present results differ considerably from those reported previously.