Electric field induced hyperfine level-crossings in (nD)Cs at two-step laser excitation: Experiment and theory

The pure electric field level-crossing of mF Zeeman sublevels of hyperfine F levels at two-step laser excitation is described theoretically and studied experimentally for the nD3/2 states in Cs with n = 7, 9 and 10, by applying a diode laser in the first 6S1/2 → 6P3/2 step and a diode or dye laser for the second 6P3/2 → nD3/2 step. Level-crossing resonance signals are observed in the nD3/2 → 6P1/2 fluorescence. A theoretical model is presented to describe quantitatively the resonance signals by correlation analysis of the optical Bloch equations in the case when an atom simultaneously interacts with two laser fields in the presence of an external dc electric field. The simulations describe well the experimental signals. The tensor polarizabilities α2 (in a03) are determined to be 7.45(20) × 104 for the 7D3/2 state and 1.183(35) × 106 for the 9D3/2 state; the electric field calibration is based on measurements of the 10D3/2 state, for which α2 is well established. The α2 value for the 7D3/2 state differs by ca. 15% from the existing experimentally measured value.