Electron-impact excitation of H-like Cr, Mn, Fe, Co, and Ni for applications in modeling X-ray astrophysical sources^⋆

¹ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
e-mail: Charles.A.Malespin@nasa.gov
² Auburn University, Auburn, AL 36849, USA

Received: 11 November 2010
Accepted: 29 November 2010

Abstract

Context. Accurate atomic data for the less abundance Fe-peak elements are required for use in X-ray astrophysical studies.

Aims. We calculate high quality electron-impact excitation collision strengths and effective collision strengths for hydrogenic Cr, Mn, Fe, Co, and Ni.

Methods. We use the Dirac R-matrix method, the intermediate coupling frame transformation R-matrix method, the semi-relativistic distorted-wave method and the fully-relativistic distorted-wave method to calculate collision strengths for each of the ions. The ADAS collisional-radiative codes are used to produce photon emissivity coefficients for each ion.

Results. Results are presented for atomic energy levels, spontaneous emission coefficients, electron-impact excitation collision strengths and associated effective collision strengths for each of the five species under consideration. We find relativistic effects can contribute an approximate 10% increase to the background cross section in relation to semi-relativistic collision calculations. We also confirm that radiation damping plays a prominent role for certain near threshold resonances. In order check the integration of our results within collisional-radiative modeling codes, we have used the ADAS package for some preliminary modeling of photon emissivities. The atomic data shall be made available online through the OPEN-ADAS site and the CFADC database