Resonance analysis in the photoionization of excited lithium below the 1s2l and 1s3l ionization thresholds of the Li atom

Calculations of 1 s electron inner-shell photoionization from the 1s 2 2p 2P a Li excited state were previously reported using the R-matrix code [Zhou et al., Phys. Rev. A 59, 462 (1999)]. These calculations included important resonances in the partial and total photoionization cross sections for incident photon energies (i) lower than 74 eV and due to the I snln'l' 2 L e >' autoionizing states for n = 2 and 3 and L = S, P, and D, and (ii) ) larger than 140 eV and due to the 2ln'l'n"l" 2Le autoionizing states. The latter resonances corresponding to 2ln'l'n"l" were recently analyzed by Zhou et al. [Phys. Rev. A 62, 012707 (2000)], using an eigenphase derivative technique along with quantum defect theory. The present paper proposes an analysis of the former resonances in the 58-74 eV incident photon energy range. The determination of the resonant positions for each series converging to a 1s2l 1 , 3 L or I s3l 1 , 3 L ionization threshold of Li is obtained using the same method as in Zhou et al. [Phys. Rev. A 62, 012707 (2000)]. The identifications are compared with theoretical results of Chung [Phys. Rev. A 57, 3518 (1998)] using the saddle-point method for energies below the Li + 1s2s 1 S threshold. Agreement is excellent in most cases and some discrepancies are discussed.