Optical-emission spectra of coreexcited Be I sL and coreexcited Be I1 ' L and 4L states have been studied by means of the beam-foil-excitation method. Multiconfigurational Hartree-Fock calculations have been performed for the optical transitions between the lower-lying Be I ' L states and between ls2pnl (n = 2-4, 1 = 0-3) 'Po, 'p, 'Do, 'De, and 'P states in coreexcited Be I1 ' L to facilitate the identifications. Some previously assigned core-excited Be I1 4L transitions are shown to belong to either the coreexcited Be I ' L or the coreexcited Be I1 *L spectrum. Additional identifications of core-excited Be I1 'L transitions explain the main features of this spectrum. The identifications of Be I1 ls2p41 4L states are discussed.

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The coreexcited quartet and doublet spectra of B 111, produced by foil excitation of fast B'-ion beams, have been studied in the wavelength region 300-63OOA. A large number of new transitions have been observed, for the first time allowing a detailed test ot theoretically predicted coreexcited B I11 4Land 'L-term schemes. For a number of quartet states, the line assignments are supported by lifetime measurements. All the assigned, core-excited spectral lines are in excellent agreement with theoretical predictions by Chung et al. These predictions have been extended to include quartet states with L > 2.

A study of the ns0np6 1S0 states in the rare gas ions is described. A large cross section for the production of two vacancies in the ns shell in certain ion-atom collisions is used to settle the dispute over the identifications of the ns0np6 states in Auger spectroscopy. The identifications due to McGuire of the 3s03p6 1S0 and 4s04p6 1S0 states in Ar III and Kr III, respectively, are confirmed. Optical spectroscopy is used to obtain accurate values for the energies of these levels. The large cross sections for the production of two ns vacancies in the rare gases in ion-atom collisions are assumed to be the reason that the ns0np6 1S0 levels are found to be strongly populated in the hollow-cathode discharge compared to light sources where electron-impact excitation dominates.

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