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A&A Supplement Series, Vol. 126, December I 1997, 373-378

Received February 28; accepted March 3, 1997

Atomic data from the Iron Project

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

H.L. Zhang and A.K. Pradhan

Send offprint request: H.L. Zhang
Department of Astronomy, The Ohio State University, Columbus, OH 43210, U.S.A.


Collision strengths and maxwellian-averaged rate coefficients have been calculated for 8771 non-vanishing transitions among 140 fine structure levels, dominated by the configurations tex2html_wrap_inline940, tex2html_wrap_inline942, and tex2html_wrap_inline944 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.

keywords: atomic processes -- planetary nebulae: general -- H II regions

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