Wavelengths of the fine-structure transition 2s 2 S 1/2 -2p 2 P 1/2 in lithiumlike Sn 47ϩ and Xe 51ϩ have been determined using beam foil excitation and grazing incidence spectroscopy. Transition wavelengths of 114.895Ϯ0.008 Å for Sn 47ϩ and 103.475Ϯ0.007 Å for Xe 51ϩ have been measured. While there has been no previous measurement of this transition in Sn, the Xe result marks an improvement in accuracy of more than an order of magnitude compared with previous experiments. The achieved precision of 70 ppm for the 1/2-1/2 transition allows for a 0.1% QED test which establishes a new benchmark for Li-like ions in the medium Z range. The experimental uncertainty is smaller than the size of the smallest calculated contribution to the transition energy.

Wavelengths of the fine structure transitions 2s 2 S 1/2 -2p 2 P 3/2 and 2s 2 S 1/2 -2p 2 P 1/2 in lithiumlike Ag 44ϩ have been measured using beam-foil excitation and grazing incidence spectroscopy. The respective transition wavelengths of 40.829Ϯ0.004 Å and of 124.685Ϯ0.009 Å 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 у24, including our recent results for Ni 25ϩ and Zn 27ϩ , is presented and compared with the best available calculations.

No abstract

Be-like Ag43+, Sn46+, and Xe50+ ions were produced by beam-foil excitation at the UNILAC accelerator of the GSI. The wavelengths of the 2s2 1S0–2s2p 3P1 intercombination lines were measured using the GSI 5 m grazing incidence spectrometer. The projectile spectra were calibrated in situ with well known ionic lines of a VUV Penning discharge lamp. A precise determination of the Doppler shift was necessary. An experimental precision of 10-4 was realized. Our medium-Z experimental results represent the heaviest Be-like ions studied. They are compared with published MCDF and MBPT calculations along the isoelectronic Be-like series. Excellent agreement exists between our Xe-value and a recent result from an electron beam ion trap.

No abstract

No abstract

No abstract