Calculation of near-threshold O- photodetachment, including fine-structure effects

The photodetachment cross section of the O-(2p52Po) ground state is studied near the O(2p43Pjc) fine-structure thresholds, using the eigenchannel R-matrix method, multichannel quantum-defect theory, and the recoupling frame transformation. We find that the cross section increases monotonically with energy near the lowest detachmnet thresholds, in contrast to the Se- photodetachment cross section studied earlier. Our calculations, which are based on ab initio methods to obtain multichannel scattering parameters, explain the near-threshold features in the O- photodetachment cross section observed in an earlier experiment. copyright 1996 The American Physical Society