Atomic data from the iron project .18. Electron impact excitation collision strengths and rate coefficients for Fe III

Collision strengths and maxwellian averaged rate coefficients have been calculated for 23 871 transitions among 219 fine structure levels, dominated by configurations 3d(6), 3d(5)4s, and 3d(5)4p in Fe III. Collision strengths are calculated using the R-matrix method with a 83 term close-coupling target expansion and for electron energies up to 10 rydbergs. Rate coefficients are tabulated at a wide range of temperatures at which Fe III is abundant in plasma sources. A brief discussion of the calculations and sample results are given. The present rates for Fe III are expected to find applications in spectral diagnostics of a variety of astrophysical sources.