Experimental investigation of the 6s2 1S0→5d6s 3D1,2 forbidden transitions in atomic ytterbium

We have observed the Stark-induced 6s(2) S-1(0)-->5d6s D-3(1) transition in Yb, and measured properties relevant to the study of atomic parity nonconservation in this transition. An atomic beam of Yb is excited by 408-nm light in the presence of an external de electric field, resulting in cascade fluorescence at 556 nm as the excitation decays through the 6s6p P-3, state. The density of the atomic beam and the fluorescence detection efficiency are calibrated by directly exciting the 6s6p P-3(1) State with 556-nm light. Using an estimate of the D-3(1)-P-3(1) branching fraction, we obtain a measurement of the vector transition polarizability, \beta\ = 2.18(33) x 10(-8) ea(0)/(V/cm). In addition, we have observed the 6s(2 1)S(0)-->5d6s D-3(2) transition at 404 nm. The electric quadrupole transition amplitude and tensor transition polarizability have been measured. We have also measured the de Stark shifts, hyperfine structure, and isotope shifts for both transitions. [S1050-2947(99)11905-X].