2s2 1S0-2s2p 3P1 intercombination transition wavelengths in Be-like Ag43+, Sn46+, and Xe50+ ions

Be-like Ag43+, Sn46+, and Xe50+ ions were produced by beam-foil excitation at the UNILAC accelerator of the GSI. The wavelengths of the 2s(2) S-1(0)-2s2p 3p(1) 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.