Atomic data from the Iron Project^*

XXVII. Electron impact excitation collision strengths and rate coefficients for Fe IV

Department of Astronomy, The Ohio State University, Columbus, OH 43210, U.S.A.

Send offprint request to: H.L. Zhang

Received: 28 February 1997
Accepted: 3 March 1997

Abstract

Collision strengths and maxwellian-averaged rate coefficients have been calculated for 8771 non-vanishing transitions among 140 fine structure levels, dominated by the configurations , , and in Fe IV. Collision strengths are calculated using the R-matrix method with a 49 term close-coupling target expansion for electron energies up to 15 rydbergs. Rate coefficients are tabulated for a wide range of temperatures in which Fe IV is abundant in plasma sources. A brief discussion of the calculations and sample results are given. The present rates for Fe IV are expected to find applications in spectral diagnostics of a variety of astrophysical sources.