Collision strengths for electron collision excitation of fine-structure levels in S III

Electron collisional excitation strengths for transitions between the 3s(2) 3p(2) P-3(0.1,2), D-1(2), and S-1(0) levels and from these levels to the fi ne-structure levels of the excited 3s3p(3), 3s(2)3p3d, 3s(2)3p4s, 3s(2)3p4p , and 3s(2)3p4d configurations of S III are calculated in R-matrix approach . We considered 49 fine-structure levels arising from the 27 LS 3s(2)3p(2) P-3, D-1, S-1, 3S3p(3 5, 3)S degrees, D-1,D- 3 degrees, P-1,P- 3 degrees, 3 s(2)3p3d(1, 3)P degrees, D-1,D-3 degrees, F-1,F- 3 degrees, 3s(2)3p4s P-1,P -3 degrees, 3s(2)3p4p S-1,S-3, P-1,P-3, D-1,D-3, 3S(2)3p4d P-1,P-3 degrees, and D-1,D-3 degrees states. These target levels are represented by fairly extensive configuration-interaction wave functions. The collision strengths for transitions between fine-structure levels are calculated by transformi ng the LS-coupled K-matrices to K-matrices in an intermediate coupling sche me. Complicated resonance structures converging to excited state thresholds are explicitly included in collision strengths. The effective collision st rengths are obtained from the total collision strengths by integrating over a Maxwellian velocity distribution. These are tabulated over a wide electr on temperature range (0.5-10) x 10(4) K.