Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions
Using the photon-ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe2+ ions in the energy range of 690-920 eV. This range contains thresholds and resonances associated with ionization and excitation o...
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Published in | The Astrophysical journal Vol. 908; no. 1; pp. 52 - 59 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Philadelphia
The American Astronomical Society
01.02.2021
IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | Using the photon-ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe2+ ions in the energy range of 690-920 eV. This range contains thresholds and resonances associated with ionization and excitation of 2p and 2s electrons. Calculations were performed to simulate the total absorption spectra. The theoretical results show very good agreement with the experimental data, if overall energy shifts of up to 2.5 eV are applied to the calculated resonance positions and assumptions are made about the initial experimental population of the various levels of the Fe2+([Ar]3d6) ground configuration. Furthermore, we performed extensive calculations of the Auger cascades that result when an electron is removed from the 2p subshell of Fe2+. These computations lead to a better agreement with the measured product-charge-state distributions as compared to earlier work. We conclude that the L-shell absorption features of low-charged iron ions are useful for identifying gas-phase iron in the interstellar medium and for discriminating against the various forms of condensed-phase iron bound to composite interstellar dust grains. |
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Bibliography: | AAS27670 Laboratory Astrophysics, Instrumentation, Software, and Data AC02-05CH11231; 05K16GUC; 05K16SJA; 05K16RG1 USDOE Office of Science (SC), Basic Energy Sciences (BES) German Federal Ministry for Education and Research (BMBF) |
ISSN: | 0004-637X 1538-4357 1538-4357 |
DOI: | 10.3847/1538-4357/abcc64 |