Abstract
Abstract
Experimental and theoretical results are presented for double, triple, and quadruple photoionization of Si+ and Si2+ ions and for double photoionization of Si3+ ions by a single photon. The experiments employed the photon–ion merged-beams technique at a synchrotron light source. The experimental photon-energy range 1835–1900 eV comprises resonances associated with the excitation of a 1s electron to higher subshells and subsequent autoionization. Energies, widths, and strengths of these resonances are extracted from high-resolution photoionization measurements, and the core-hole lifetime of K-shell ionized neutral silicon is inferred. In addition, theoretical cross sections for photoabsorption and multiple photoionization were obtained from large-scale multiconfiguration Dirac–Hartree–Fock calculations. The present calculations agree with the experiment much better than previously published theoretical results. The importance of an accurate energy calibration of laboratory data is pointed out. The present benchmark results are particularly useful for discriminating between silicon absorption in the gaseous and in the solid component (dust grains) of the interstellar medium.
Funder
Deutsche Forschungsgemeinschaft
Bundesministerium für Bildung und Forschung
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
3 articles.
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