Electron Scattering from Neutral Fe and Low-energy Photodetachment of Fe−

Abstract

Abstract Extensive calculations are reported for electron collision strengths and rate coefficients for a wide range of transitions in Fe i. The calculations were carried out with the B-spline R-matrix method. A multiconfiguration Hartree–Fock method with nonorthogonal, term-dependent orbitals was employed to generate accurate initial- and final-state wave functions. The close-coupling expansion contained 221 LS states of Fe and included all levels of the , , , , and configurations. Effective collision strengths were obtained by averaging the electron collision strengths over a Maxwellian speed distribution at electron temperatures ranging from 102 to 105 K. They were tabulated for 24,531 transitions between all LS-terms included in the close-coupling expansion. The present results considerably expand on the few existing data sets for Fe i. They enable more detailed treatments of the available measured spectra from various observatories than previously possible. In particular, nonlocal thermodynamic equilibrium modeling of late-type stars, where large amounts of collisional data for the atomic species of interest are required, can be performed. The same close-coupling expansion was used to study low-energy photodetachment of Fe−, where the cross sections exhibit prominent resonance features. Good agreement with the few existing experimental values for partial cross sections to specific final target states of Fe was obtained.