Electron impact excitation of the2Poto4Petransition in S IV

The authors present collision strengths for the 3s 2 3p 2 P o to 3s3P 24 P e transition in S IV calculated using the R-matrix method. At low energies the cross section is dominated by resonances which are considered in detail for two partial waves. Collision rates for a Maxwellian distribution are larger than previous values and in better agreement with those implied by observations of S IV emission lines in the solar spectrum.