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 which is proportional to kE ×P, where P is the spin-polarization vector and k is the direction of observation. The effect is due to interference between spontaneous magnetic-dipole (M 1) and induced electric-dipole (E 1) decay modes to the ground state. At |E|=38.14 V/cm, the measured asymmetry is (0.3230.085) × 10-3 in agreement with the theoretical value 0.3443 × 10-3. The experiment provides the first measurement of the relativistic M 1 matrix element for the 2s12-1s12 transition in a hydrogenic ion. The paper contains an extensive discussion of all possible asymmetry effects, including higher-order relativistic and electric-field perturbation corrections. © 1982 The American Physical Society.
Van Wijngaarden, A. and Drake, Gordon W. F.. (1982). Measurements of an e 1-M 1 interference effect in the electric-field quenching of spin-polarized He+2s12 ions. Physical Review A, 25 (1), 400-410.