Physical Review A
Accurate values of the Lamb shift can be derived from measurements of the anisotropy in the angular distribution of the radiation accompanying the electric field induced 2s-1s transition of hydrogen. Calculations of the anisotropy, including relativistic and hyperfine structure corrections, are presented for the hydrogenic ions up to S15+. The data enable the calculation of the Lamb shift from a measured value of the anisotropy. © 1976 The American Physical Society.
Drake, Gordon W. F. and Lin, C. P.. (1976). Calculated anisotropies for the quenching radiation in the hydrogen isoelectronic sequence. Physical Review A, 14 (3), 1296-1298.