No abstract

In previous papers formulas for mean wave numbers and spectral widths of transition arrays have been presented. Here the method is extended to the cases nl n'lj'-nl n "lj", (nlj) n'lj'-(nlj) n "lz", and (nlj) +'-(nlj) n'l~', i.e. , when the spectrum exhibits several subarrays, due to the effects of large spin-orbit interactions. The first case is typical of the x-ray transitions between the internal subshells of the atom. The second and the third cases occur in the vuv and x-ray spectra of highly ionized heavy atoms. The evolution of the array 3d 4s-3d 4p along the isoelectronic sequence is presented as a first example of calculation, and criteria for the choice of the relevant formula are proposed. A second example is that of the 3d -3d 4p array in the spectrum of tungsten. Formulas are given (in the Appendices) for the total intensities of subarrays and for the variances of the distribution of energy levels in subconfigurations of the types nl n'lJ' and ( nl~) (n'l~' )

We propose a hybrid approach to treating atomic structure and rates in collisionalradiative models, combining the completeness of highly averaged models with the accuracy of detailed models. The hybrid scheme supplements a small subset of coronally accessible fine structure levels with a complete set of configuration-and superconfiguration-averaged levels and produces spectra based on transitions among a mix of fine-structure and relativistic configuration-averaged levels. Convenient expressions are given for obtaining rates between the fine structure and averaged levels and a technique for propagating configuration interaction from the fine structure calculations to configuration averages is described. We present results from a trial hybrid model of germanium which demonstrate the accuracy of the hybrid model for charge state distributions and spectra.