Inner-shell photoionization studies of neutral atomic nitrogen
- Department of Chemistry, University of Nevada, Las Vegas, NV 89154 (United States)
- Institute of Theoretical Physics and Astronomy, Vilnius University, Goštauto St. 12, LT-01108 Vilnius (Lithuania)
- Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro (Brazil)
- Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
Inner-shell ionization of a 1s electron by either photons or electrons is important for X-ray photoionized objects such as active galactic nuclei and electron-ionized sources such as supernova remnants. Modeling and interpreting observations of such objects requires accurate predictions for the charge state distribution (CSD), which results as the 1s-hole system stabilizes. Due to the complexity of the complete stabilization process, few modern calculations exist and the community currently relies on 40-year-old atomic data. Here, we present a combined experimental and theoretical study for inner-shell photoionization of neutral atomic nitrogen for photon energies of 403–475 eV. Results are reported for the total ion yield cross section, for the branching ratios for formation of N{sup +}, N{sup 2+}, and N{sup 3+}, and for the average charge state. We find significant differences when comparing to the data currently available to the astrophysics community. For example, while the branching ratio to N{sup 2+} is somewhat reduced, that for N{sup +} is greatly increased, and that to N{sup 3+}, which was predicted to be zero, grows to ≈10% at the higher photon energies studied. This work demonstrates some of the shortcomings in the theoretical CSD data base for inner-shell ionization and points the way for the improvements needed to more reliably model the role of inner-shell ionization of cosmic plasmas.
- OSTI ID:
- 22887009
- Journal Information:
- Astrophysical Journal, Vol. 818, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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