Va. Yerokhin et al., Two-photon exchange corrections to the 2p(1/2)-2s transition energy in Li-like high-Z ions, PHYS REV L, 85(22), 2000, pp. 4699-4702
A rigorous QED calculation of the two-photon exchange corrections to the 2P
(1)/(2)-2S transition energy in Li-like high-Z ions is presented. The contr
ibution due to an exchange by more than two photons is evaluated within the
Breit approximation. The resulting theoretical value of the 2P1/2-2S trans
ition energy in Li-like uranium is found to be 280.44(20) eV.