Physical Review A
When a beam of spin-polarized metastable He+2s12 ions is quenched by an electric field E, the emitted radiation intensity contains an asymmetry term proportional to (kE)(P'k×E) where P' is the spin-polarization vector and k is the direction of observation. The resulting asymmetry is nearly proportional to the level width of the 2p12 state in He+. The experiment provides the first observation of the asymmetry. The measured asymmetry is (0.007 69±0.000 10) in agreement with the theoretical value 0.007 618 and corresponds to a lifetime 2p=(0.988±0.013)×10-10 sec. © 1982 The American Physical Society.
Van Wijngaarden, A.; Helbing, R.; Patel, J.; and Drake, Gordon W. F.. (1982). E1-E1 damping interference in the electric field quenching of spin-polarized He+2s12 ions. Physical Review A, 25 (2), 862-868.