E1-M1 DAMPING INTERFERENCE IN THE ELECTRIC-FIELD QUENCHING OF METASTABLE AR17+ IONS

We have confirmed the prediction of a pseudo-time-reversal-odd anisotr opy proportional to (E) over right arrow.(k) over cap in the decay of metastable (2s(1/2)) Ar17+ ions in an electric field (E) over right ar row, where (k) over cap is the direction of observation. The anisotrop y arises from interference between the Mi and induced El amplitudes fo r the decay. Theory predicts that the pseudo-T-odd invariant should co ntribute to the angular distribution through a term associated with th e damping (finite lifetime) of the 2p levels. The decay rate for the i nterference term is found to be -1.64(0.12) s(-1) sr(-1) (V/cm)(-1). T his corresponds to a 2s Lamb shift for Ar17+ of 38.6(1.4) THz.