Wavelengths of the fine structure transitions 2s S-2(1/2)-2p P-2(3/2) and 2s S-2(1/2)-2p P-2(1/2) in lithiumlike Ag44+ have been measured using beam-foil excitation and grazing incidence spectroscopy. The respective transition wavelengths of 40.829+/-0.004 Angstrom and of 124.685+/-0.009 Angstrom were not measured before for this ion. The achieved precision of 70 ppm for the 1/2-1/2 transition allows for a 0.2% QED test which sets a new benchmark in the medium Z range. Our experimental uncertainty is smaller than calculated two-photon exchange contributions to the transition energy. A summary of all published experimental data along the isoelectronic sequence for Z greater than or equal to 24, including our recent results: for Ni25+ and Zn27+. is presented and compared with the best available calculations. [S1050-2947(99)02703-1].

We have measured 2s–2p fine structure transition energies in highly charged Ni, Zn, and Ag ions using beam–foil excitation and grazing incidence spectroscopy at the GSI–UNILAC accelerator. The precision of the results provides tests of two-photon QED screening corrections to the 2s–2p transition energies. The experimental values are compared with other measurements and with recent relativistic calculations along the lithium–isoelectronic sequence.

N=3, \(\) intercombination transitions in Al-like ions of Au have been studied by time-resolved EUV spectroscopy of foil-excited ion beams. Wavelengths and lifetimes are compared to the available relativistic calculations. The theoretical data are found to be useful for guidance, but of clearly insufficient precision, in particular for the transition probabilities.

The angular asymmetry parameter of the photon-induced fluorescence radiation of fine-structure resolved satellite lines was measured from threshold up to 38.4 eV. It is well known that the cross sections of these valence shell satellites are dominated by the decay of aligned doubly excited states leading to an extremely complicated energy dependence. In contrast, we observe that the parameter becomes less structured with increasing total angular momentum J of the photoion. The measurements can be interpreted by a partial-wave analysis of the photofragmentation products. For the population of the ion state only photoelectrons are emitted on all resonances. For the population of the and the ion states the emission of the parity-unfavoured photoelectrons dominates.

Wavelengths of the fine-structure transitions 2s S-2(1/2)-2P P-2(3/2) and 2s S-2(1/2)-2p P-2(1/2) in lithiumlike Ni25+ and Zn27+ have been measured using beam-foil excitation and grazing-incidence spectroscopy. The respective transition wavelengths of 142.461 +/- 0.006 Angstrom and of 216.061 +/- 0.011 Angstrom for Zn27+ have not been measured so far and present the most precise values in lithiumlike heavy ions measured by beam-foil spectroscopy. The Ni25+ results are in very good agreement with data from grazing-incidence spectroscopy at tokamaks. The measurement precision for both ions corresponds to less than or equal to 1% of the quantum electrodynamic contributions to the transition energies. This provides sensitivity to two-photon exchange processes for the screening of the electron self-energy. [S1050-2947(98)04310-8].

N=3, Δn=0 transitions in Na-like ions have been observed and the resonance level lifetimes have been measured by time-resolved spectroscopy of foil-excited ion beams of Xe (Z=54) and Au (Z=79). Other lines in the same wavelength range are identified withn=3, Δn=0 transitions in Ne-, Mg-, and Al-like ions. Wavelengths and transition rates for these new lines are compared to the available theoretical data. A number of experimental problems are discussed.

The wavelength of the 2s 2 S 1 2 −2p 2 P 3 2 transition in Li-like Ni was measured, using for the first time beam-foil spectroscopy. Ni13+ ions at 5.95 MeV/u and 11.68 MeV/u UNILAC-energies were excited by 200 μg/cm2 and 100 μg/cm2 carbon foils. A value of 16.5366 nm has been obtained with an accuracy of 0.0024 nm, corresponding to 1.8% of the QED contribution to the 2s–2p transition energy. The experimental procedure, based on an in situ wavelength calibration and a Doppler shift correction, is described. A comparison of the result with values from measurements at tokamaks and with calculations is carried out.

The wavelength of the 2s(2)S(1/2)-2p(2)P(3/2) transition in Li-like Ni was measured, using for the first time beam-foil spectroscopy; Ni13+ ions at 5.95 MeV/u and 11.68 MeV/u UNILAC-energies were excited by 200 mu g/cm(2) and 100 mu g/cm(2) carbon foils. A value of 16.5366 nm has been obtained with an accuracy of 0.0024 nm, corresponding to 1.8% of the QED contribution to the 2s-2p transition energy. The experimental procedure, based on an in situ wavelength calibration and a Doppler shift correction, is described. A comparison of the result with values from measurements at tokamaks and with calculations is carried out.

The wavelength of the 2s2S12−2p2P32 transition in Li-like Ni was measured, using for the first time beam-foil spectroscopy. Ni13+ ions at 5.95 MeV/u and 11.68 MeV/u UNILAC-energies were excited by 200 μg/cm2 and 100 μg/cm2 carbon foils. A value of 16.5366 nm has been obtained with an accuracy of 0.0024 nm, corresponding to 1.8% of the QED contribution to the 2s–2p transition energy. The experimental procedure, based on an in situ wavelength calibration and a Doppler shift correction, is described. A comparison of the result with values from measurements at tokamaks and with calculations is carried out.

The lifetimes of the 3p 2P° resonance levels and of the 3d 2D levels in Na-like ions Xe43+ (Z = 54) and Au68+ (Z = 79) have been measured by time-resolved spectroscopy of foil-excited ion beams. This represents a major step beyond the previous data which reached only up to Z=29, into the range with massive relativistic effects. The results corroborate the lifetimes predicted by very recent calculations of the atomic structure which also reproduce the experimental transition wavelengths.