Innershell Photoionization Studies of Neutral Atomic Nitrogen

Stolte, W. C.; Jonauskas, V.; Lindle, D. W.; Sant'Anna, M. M.; Savin, Daniel Wolf

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 + , N2+, and N3+, 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 N2+ is somewhat reduced, that for N + is greatly increased, and that to N3+, 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 innershell ionization of cosmic plasmas.


Also Published In

The Astrophysical Journal

More About This Work

Academic Units
Astrophysics Laboratory
Published Here
September 6, 2017