Steps toward dielectronic recombination of argon-like ions: A revisited theoretical investigation of Sc and Ti

As an improvement to an earlier study [T.W. Gorczyca, M.S. Pindzola, F. Robicheaux, N.R. Badnell, Phys. Rev. A 56 (1997) 4742], we have calculated dielectronic recombination rate coefficient spectra for Sc and Ti ions as a test case toward the assembly of a database [http://homepages.wmich.edu/~gorczyca/drdata/] for the Ar-like isoelectronic sequence required for modeling of dynamic finitedensity plasmas [N.R. Badnell et al., A&A 406 (2003) 1151]. Our theoretical spectra contain dominant DN = 0 and DN = 1 core excitations channels and exhibit nearly all features found in a recent ion storage ring experiments [S. Schippers, T. Bartsch, C. Brandau, G. Gwinner, J. Linkemann, A. Müller, A.A. Saghiri, A. Wolf, J. Phys. B 31 (1998) 4873; S. Schippers et al., Phys. Rev. A 65 (2002) 042723]. In order to compare Maxwellian-averaged rate coefficients, which are of main interest to the astrophysics community, we have developed an iterative deconvolution procedure that enables us to extract the cross-section from storage ring data. After folding the resultant cross-section with a Maxwellian electron velocity distribution, theoretical and experimental rate coefficient spectra agree better than 18% subject to field reionization effects via high Rydberg states in Sc and Ti ions. 2007 Elsevier B.V. All rights reserved. PACS: 31.10.+z; 32.80.Dz; 34.80.Lx