Physical Review A
The quenching of hydrogenic metastables is formulated as a near-resonant photon-scattering problem, and a complete analysis of the polarization and angular distribution of the emitted radiation is presented. The contribution from np states with n>2 is calculated, and an alternative method of measuring the Lamb shift is suggested. © 1973 The American Physical Society.
Drake, Gordon W. F. and Grimley, R. B.. (1973). Photon-scattering theory of the quenching of hydrogenic metastables. Physical Review A, 8 (1), 157-160.