No abstract

We have used a sensitive laser polarimeter to measure the electric-field-induced dichroism on the transition 4f66s2 'F,-4f66s6p 'GI of Sm I at A639 nm. The dichroism gives an apparent (pseudo) optical rotation which can be sensitively detected using a Faraday modulator in the polarimeter. The results are interpreted in terms of the electric field coupling between the upper state of the transition and the nearby 4f66s5d 'GI level which lies only 322 GHz away. The value of the Stark matrix element /(4f66s5d 'G,~ler~/4f66s6p 'GJ has been determined to be 0.85 (5) ea,, in broad agreement with theoretical estimates. Effects due to optical pumping and saturation caused by increased laser power have been observed and the theory of these phenomena is briefly reviewed. The transition 4f66s2 'F,-4f66s5d 'GI has also been detected by laser polarimetry using electric field enhancement.

An experimental study has been made of the nearly degenerate, opposite parity states 4f 66s6p 7G1 and 4f 65d6s 7G1 in samarium to assess the feasibility of using the forbidden M1 transition from the 4f 66s 2 7F0 ground state to the 4f 65d6s 7G1 state for measuring parity non-conserving (PNC) effects. The authors conclude that detection of the PNC optical rotation is not feasible because of the high background rotation present at the M1 wavelength and also because the PNC signal itself would be significantly smaller than in existing PNC experiments. Consideration has also been given to the possibility of a novel optical rotation experiment on this transition, using crossed electric and magnetic fields. However, this too is concluded not to be feasible due to the difficulty in achieving a sufficiently large PNC signal. A general comment on the future of rare earth elements for PNC studies is made.