Calculations of inner-shell photoionization of 1s 2 2p 2 P o and 1s 2 3p 2 P o Li excited states have been performed using recent developments of the R-matrix code with a 29-term target representation for incident photon energies up to 165 eV, with particular emphasis on multiple electron processes. Partial and total cross sections are given for a number of excitation processes including the lower members of 19 hollow atom resonance series. The results are compared with recent experimental measurements of the lowest 2s2p 2 2 L e resonance of even-parity hollow lithium states produced by photoexcitation of laser-excited lithium atoms. Experiment and theory are in excellent agreement on a relative scale. The enhancement of the shake-up process increases with initial state excitation, up to 500% over that of the ground state for 1s 2 3p 2 P o . Good agreement is also obtained for K-shell photoionization when comparing branching ratios with available experimental results.

Using a dilute atomic beam of lithium crossed with monochromatized vacuum-ultraviolet synchrotron radiation from the undulator beamline BW3 at HASYLAB, the resulting singly ionized lithium signal was measured in the photon energy region corresponding to the threshold for inner-shell excitation. The photoion spectra were measured with a photon energy resolution of approximately 10000, facilitating the identification of a number of window-type resonances above the threshold. New R-matrix calculations are also presented which show good agreement with the observed relative intensity variation of the experimental data.

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Photoion and photoelectron data for hollow lithium states were recently reported with increased spectral resolution. In order to reproduce and identify the important resonances due to 2lnЈlЈnЉlЉ 2 P o autoionizing states new photoionization calculations have been performed using the R-matrix code with a 29-term target representation for incident photon energies between 140 and 167 eV. Excellent agreement between theoretical and measured results over partial or total photoionization cross sections confirms the quality of the theoretical model. A determination of the resonance positions for each series converging to a 2l2lЈ 1,3 L threshold of Li is proposed.

Calculations of 1s electron inner-shell photoionization from the 1s 2 2s 2 S e Li ground state have been performed using recent developments of the R-matrix code with a 19-term target representation for incident photon energies up to 130 eV. This photon energy range allows important resonances in the partial cross sections due to 1snlnЈlЈ autoionizing states to be obtained. Theoretical resonant results are compared with recent experimental measurements of Kiernan et al. ͓J. Phys. B 29, L181 ͑1996͔͒ in the 1s2l threshold region. Partial cross sections, branching ratios, and asymmetry parameters are also compared outside the resonant energy range with previous theoretical results of Lisini, Burke, and Hibbert ͓J. Phys. B 23, 3767 ͑1990͔͒, who used the R-matrix code with an 11-term target representation, as well as the corresponding experimental results of Ferret et al. ͓Phys. Rev. A 36, 3172 ͑1987͔͒, Langer et al. ͓Phys. Rev. A 43, 1652 ͑1991͔͒, and Cubaynes et al. ͑private communication͒.

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The photodetachment cross section of the 1s2s2p 4 P o metastable state of He Ϫ in the region of the 1s threshold has been calculated using our enhanced R-matrix code with the asymptotic part upgraded to handle a negative-ion system. The results show a 1s photodetachment cross section with numerous structures, completely different from similar situations in atoms or positive ions. This is found to be due to the dominance of correlation of both initial and final states of the negative ion. Specifically, interchannel coupling and a newly identified multiconfiguration overlap effect are primarily responsible for the dramatic 1s photodetachment cross-section phenomenology. Comparison with a previous calculation has been made and, while there are some areas of excellent agreement, overall there are very serious discrepancies, as much as an order of magnitude.