Electron-impact excitation of forbidden and allowed transitions in Cr II

Abstract

Synopsis The B-spline R-matrix method is used to investigate the electron-impact excitation of Cr II. The close-coupling expansion contains 512 fine-structure levels of Cr II and includes all levels of the 3d5, 3d44s, 3d34s2, 3d44p and 3d34s4p configurations. The present results considerably expand the existing data sets for Cr II, allowing a more detailed treatment of the available measured spectra from different space observatories.