Self-Consistent R-matrix Approach To Photoionization And Unified Electron-Ion Recombination

Abstract

A unified scheme using the R-matrix method has been developed for electron-ion recombination subsuming heretofore separate treatments of radiative and dielectronic recombination (RR and DR). The ab initio coupled channel approach unifies resonant and non-resonant phenomena, and enables a general and self-consistent treatment of photoionization and electron-ion recombination employing idential wavefunction expansion. Detailed balance takes account of interference effects due to resonances in cross sections, calculated explicitly for a large number of recombined (e+ion) bound levels over extended energy regions. The theory of DR by Bell and Seaton is adapted for high-n resonances in the region below series limits. The R-matrix method is employed for (A) partial and total photoionization and photorecombination cross sections of (e+ion) bound levels, and (B) DR and (e+ion) scattering cross sections. Relativistic effects and fine structure are considered in the Breit-Pauli approximation. Effects such as radiation damping may be taken into account where necessary. Unfiied recombination cross sections are in excellent agreement with measurements on ion storage rings to about 10-20%. In addition to high accuracy, the strengths of the method are: (I) both total and level-specific cross sections and rate coefficients are obtained, and (II) a single (e+ion) recombination rate coefficient for any given atom or ion is obtained over the entire temperature range of practical importance in laboratory and astrophysical plasmas, (III) self-consistent results are obtained for photoionization and recombination; comprehensive datasets have been computed for over 50 atoms and ions. Selected data are presented for iron ions.

33 pages, 13 figures, Review in "Radiation Processes In Physics and Chemistry", Elsevier (in press). Postscript file with higher resolution figures at http://www.astronomy.ohio-state.edu/~pradhan/pr.ps

Cited by in corpus (9)

• Theoretical FeI/II/III Emission-Line Strengths from Active Galactic Nuclei with Broad-Line Regions
• Formation of MnI lines in the solar atmosphere
• Highly Excited Core Resonances in Photoionization of Fe XVII : Implications for Plasma Opacities
• Electron impact excitation of Helium-like ions up to n=4 levels including radiation damping
• Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements VIII. Ar XIII with new features
• Recombination Rate Coefficients for KLL Di-electronic Satellite Lines of Fe XXV and Ni XXVII
• Resolution and accuracy of resonances in R-matrix cross sections
• Atomic data activities by the OP and IP consortia: past, present and new perspectives within the VAMDC
• The Iron Project and the RmaX Project