Atomic-beam study of the stark effect in the cesium and rubidium D lines

Details of a new atomic-beam method for the study of the Stark effect in optical transition are presented. The method is then applied to a study of the transitions 6p12,3226s122 in cesium and 5p12,3225s122 in rubidium. The splitting by the electric field of the p32 level into two levels is observed. It is shown that the characterization of the Stark effect in the p2 levels by a simple scalar and tensor polarizability does not hold. Fine-structure effects giving rise to differences of the p122 and p322 radial functions are sufficiently strong that the Stark effect of the p2 level must be expressed in terms of three parameters. If the polarizability α(np2mJJ) is defined by the relation ΔW(np2mJJ)=-12E2α(np2mJJ), where E is the electric field and ΔW the induced energy shift, then the following values of the polarizabilities are deduced. For cesium, α(6p122)=187 (29)×10-24 cm3; α(6p322±32)=196 (30)×10-24 cm3; and α(6p322±12)=273 (42)×10-24 cm3. For rubidium, α(5p122)=112 (17)×10-24 cm3; α(5p322)=102 (15)×10-24 cm3; and α(5p322±12)=148 (23)×10-24 cm3. The polarizabilities are compared with results deduced from Stone's recent oscillator-strength calculations for cesium and with values deduced from the method of Bates and Damgaard.