Two-electron Lamb shifts and 1s2s³S₁-1s2p³PJtransition frequencies in helium-like ions

The leading terms in the 1/Z expansion of the two-electron Bethe logarithm are calculated for the states 1s 2 1 S 0 , 1s2s 1 S 1 , 1s2s 3 S 1 , 1s2p 1 P 1 and 1s2p 3 P J by the use of a novel finite basis set method. The resulting QED terms are combined with other relativistic and mass polarisation corrections to obtain total transition frequencies. The results are compared with recent measurements in helium-like ions from Li + to Fe 24+ .