Influence of the autoionization in the calculation of the fluorescence polarization for the A 2Πu –X 2Πg transition in O+2

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Abstract
An ab initio calculation of the fluorescence polarization including autoionization is made in the case of O+2, using the multichannel quantum defect approach. If only the states belonging to Rydberg series converging to the b 4∑−g state of O+2 are included, due to their narrow ab initio calculated autoionization widths, the values of the polarization of the A 2Πu −X 2Πg fluorescence is found to be negative in the 73–69 nm wavelength region, in contradiction with recent experiments [Keller et al., J. Chem. Phys. 87, 3299 (1987)]. Good agreement with experimental results is obtained only in taking into account the influence of the 3∑−u Rydberg state (B 2∑−g) 4pσu, which enlarges the autoionized peaks either by perturbation or by predissociation. There results are compared to the qualitative theoretical interpretation of Keller et al. in terms of two 3∑−u valence states.