We report on detailed calculations of dielectronic recombination (DR) rate coefficients for Sn4 +-Sn13 + using three approaches of differing degrees of complexity. These are configuration-mixed Breit-Pauli using the autostructure code, bundled-nl using the Burgess-Bethe general program (BBGP) and configuration average (CA) using the DRACULA code. We find that target Δn = 0 dipole promotions dominate the total DR rate coefficients; configuration-mixing effects are small for the totals; results for the totals are highly dependent on the initial levels averaged over - the results for averaging over all levels of the ground configuration being typically nearly a factor of 2 smaller than for using only the ground level. On comparing the total DR rate coefficients obtained using the three methods we find that the BBGP results are systematically lower than those obtained from autostructure - in some cases they are significantly lower (by a factor of 2) - while the CA results are systematically and significantly higher (by up to 80%) in general. These findings need to be borne in mind for the finite-density modelling of tin plasma sources for microlithography and tin markers for magnetic fusion plasmas especially when using simple descriptions of DR. They apply also to heavy species in general such as tungsten ions which are of great importance for magnetic fusion plasmas.
|Journal||Journal of Physics B: Atomic, Molecular and Optical Physics|
|Publication status||Published - 14 Jul 2011|