Low-energy fine-structure resonances in photoionization of O ii
Abstract
Resonant features in low-energy photoionization cross sections are reported in coupled-channel calculations for O ii including relativistic fine structure. The calculations reveal extensive near-threshold resonant structures in the small energy region between the fine structure levels of the ground state 2p2(3P0,1,2) of the residual ion O iii. Although the resonances have not yet been observed, they are similar to other experimentally observed features. They are expected to significantly enhance the very-low-temperature dielectronic recombination rates, potentially leading to the resolution of an outstanding nebular abundances anomaly. Higher energy partial and total photoionization cross sections of the ground configuration levels 2p3(4S3/2o,2D3/2,5/2o,2P1/2,3/2o) are found to be in agreement with experimental measurements on synchrotron-based photon sources [1-3], thereby identifying the excited O iii levels present in the ion beams. These are also the first results from a recently developed version of Breit-Pauli R-matrix (BPRM) codes, with inclusion of two-body magnetic interaction terms. The improved relativistic treatment could be important for other astrophysical applications and for more precise benchmarking of experimental measurements.
- Publication:
-
Physical Review A
- Pub Date:
- December 2010
- DOI:
- 10.1103/PhysRevA.82.065401
- Bibcode:
- 2010PhRvA..82f5401N
- Keywords:
-
- 32.80.Fb;
- 95.30.Ky;
- Photoionization of atoms and ions;
- Atomic and molecular data spectra and spectral parameters