Absolute Photoionization Cross Section Measurements of O II Ions from 29.7 to 46.2 eV
Creators:Nahar, Sultana Nurun
Covington, A. M.
Phaneuf, R. A.
Bozek, J. D.
Sant'Anna, M. M.
Schlachter, A. S.
McLaughlin, B. M.
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Citation:Aguilar, A., Covington, A. M., Hinojosa, G., Phaneuf, R. A., Alvarez, I., Cisneros, C., Bozek, J. D., Dominguez, I., Sant'Anna, M. M., Schlachter, A. S., Nahar, Sultana Nurun, McLaughlin, B. M. "Absolute Photoionization Cross Section Measurements of O II Ions from 29.7 to 46.2 eV," The Astrophysical Journal Supplement Series, v146, n2, (June, 2003), pp. 467-477.
Absolute photoionization cross sections have been measured for a mixture of ground-state and metastable O II (O^+) ions at photon energies ranging from 29.9 to 46.0 eV (414.7 to 269.5 Å). All measurements were performed by merging an O^+ beam with synchrotron radiation from an undulator beam line at the Advanced Light Source (ALS). At a resolution of 17 meV, more than 70 spectral features have been resolved, most of them identified and characterized. These measurements are compared with two independent R-matrix calculations and the data in TOPbase. All three calculations agree within 25% on the direct photoionization cross section, and with the absolute measurements within 40%. Some differences are noted in the predicted resonance positions among the three close-coupling R-matrix calculations, the TOPbase data being the least accurate. The estimated total experimental uncertainty varies from 15% to 20%. Such measurements benchmark theoretical photoionization cross section calculations performed within the framework of the Opacity Project and the Iron Project.
Relevant data is available at: http://www.astronomy.ohio-state.edu/~nahar/nahar_radiativeatomicdata/index.html
This collaborative research was supported in part by the DOE Division of Chemical Sciences, Geosciences, and Biosciences from grant DE-FG03-97ER14787, by the DOE Facilities Initiative, by Nevada DOE/EPSCoR and by CONACyT.