Photoionization of Lithium Below the Li^+ 1s3s^3S Threshold

A parentage projection method is used to study the detailed ^2P^o resonances of Li between the Li^+ 1s2p ^1P and 1s3s ^3S thresholds. This method is simple and it is independent of the basis function used. Seventeen resonances are uncovered in the photoionization spectra between 71 to 74 eV. The energy, width, and resonance structures are presented. In this energy region, two high resolution experimental spectra exist due to different calibration procedures. Our predicted photoionization cross section (PICS) profile agrees closely with one of the spectra to a few meV level and disagrees with the other spectrum. There have been some discrepancies concerning the experimental Li [1s(3s3p)^3S]^2P^o energies in the literature. Our result show that the resonance energy is at 71.154 eV and the peak intensity is at 71.144 eV.