The Lamb shift of excited S-levels in hydrogen and deuterium atoms

A specific combination of s-state Lamb shift Delta E(L)(1s(1/2))- n(3) Delta E(L)(ns(1/2)) is considered. Its value is calculated both in the hydrogen and deuterium atoms for n up to 12. The result includes all correction which can contribute more than 1 kHz, particularly the one-loop corrections for both the self energy and the vacuum polarization, and the two-loop contribution. Nuclear finite-size corrections for the isotopic difference of the combination are also evaluated.