Absolute Single Photoionization of Se~(3+) Ions for the Determination of Elemental Abundances in Astrophysical Nebulae

摘要

The determination of elemental abundances in astrophysical nebulae is highly dependent on the availability of accurate atomic data. Numerical simulations show that derived selenium abundances in ionized nebulae can be uncertain by factors of two or more due to atomic data uncertainties alone. In particular, selenium abundance determinations are strongly sensitive to uncertainties in photoionization cross-sections. Absolute single photoionization cross sections for Se~(3+) ions have been measured from 42 eV to 54 eV at the Advanced Light Source at Lawrence Berkeley National Laboratory using the merged beams photo-ion technique. Theoretical photoionization cross section calculations were performed for these ions using the state-of-the-art fully relativistic Dirac R-matrix code (DARC).