Near L-edge Single and Multiple Photoionization of Singly Charged Iron Ions
- I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)
- Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)
- Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena (Germany)
- FS-SCS, DESY, Notkestraße 85, 22607 Hamburg (Germany)
- FS-PE, DESY, Notkestraße 85, 22607 Hamburg (Germany)
- Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)
- Institut für Atom- und Molekülphysik, Justus-Liebig-Universität Gießen, Leihgesterner Weg 217, 35392 Giessen (Germany)
Absolute cross-sections for m-fold photoionization (m=1, …, 6) of Fe{sup +} by a single photon were measured employing the photon–ion merged-beams setup PIPE at the PETRA III synchrotron light source, operated by DESY in Hamburg, Germany. Photon energies were in the range 680–920 eV, which covers the photoionization resonances associated with 2p and 2s excitation to higher atomic shells as well as the thresholds for 2p and 2s ionization. The corresponding resonance positions were measured with an uncertainty of ±0.2 eV. The cross-section for Fe{sup +} photoabsorption is derived as the sum of the individually measured cross-sections for m-fold ionization. Calculations of the Fe{sup +} absorption cross-sections were carried out using two different theoretical approaches, Hartree–Fock including relativistic extensions and fully relativistic multiconfiguration Dirac–Fock. Apart from overall energy shifts of up to about 3 eV, the theoretical cross-sections are in good agreement with each other and with the experimental results. In addition, the complex de-excitation cascades after the creation of inner-shell holes in the Fe{sup +} ion were tracked on the atomic fine-structure level. The corresponding theoretical results for the product charge-state distributions are in much better agreement with the experimental data than previously published configuration-average results. The present experimental and theoretical results are valuable for opacity calculations and are expected to pave the way to a more accurate determination of the iron abundance in the interstellar medium.
- OSTI ID:
- 22875671
- Journal Information:
- Astrophysical Journal, Vol. 849, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoionization of Ne Atoms and Ne{sup +} Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections
Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions