Oscillator strengths and transition probabilities of O II

Abstract

The abundance of singly ionized oxygen, O II, in planetary nebulae provides crucial diagnostic tests for the physical conditions present in these astrophysical environments. The abundance can be determined from the absorption lines formed by the radiative processes, such as the photo-excitations reported here. Radiative transitions are obtained from a total of 708 fine structure levels of O II with n ⩽ 10 , l ⩽ 9 , and 1 / 2 ⩽ J ⩽ 17 / 2 . For spectral analysis oscillator strengths, line strengths, and transition probabilities ( A ) are presented for 51,733 electric dipole fine structure radiative transitions. The calculations were carried out in the relativistic Breit–Pauli R-matrix approximation. The transitions have been identified spectroscopically using quantum defect analysis and other criteria. The calculated energies agree with the observed energies within 5% for most of the levels. However, some relatively large differences are noted, the largest difference being 13% for the level 2 s 2 2 p 2 ( 1 D ) 4 p ( 2 F o ) 7 / 2 . Most of the A values and lifetimes agree with the existing measured and calculated values. The transitions should be applicable for diagnostics as well as spectral modeling in the ultraviolet and optical regions of astrophysical and laboratory plasmas.