Photorecombination of berylliumlike and boronlike silicon ions

Abstract

We report measured rate coefficients for electron-ion recombination for Si 10+ forming Si 9+ and for Si 9+ forming Si 8+ , respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si 9+ and from 0 to 2000 eV for Si 10+ , thus, extending previous measurements for Si 10+ [Orban et al 2010 Astrophys. J. 721 1603] to much higher energies. Experimentally derived rate coefficients for the recombination of Si 9+ and Si 10+ ions in a plasma are presented along with simple parameterizations. These rate coefficients are useful for the modeling of the charge balance of silicon in photoionized plasmas (Si 9+ and Si 10+ ) and in collisionally ionized plasmas (Si 10+ only). In the corresponding temperature ranges, the experimentally derived rate coefficients agree with the latest corresponding theoretical results within the experimental uncertainties.