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 IV

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.
e-mail: zhang@payne.mps.ohio-state.edu

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.

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

• 1. Introduction
• 2. Atomic calculations
• 3. Results
• 4. Discussion and conclusion
• References