High Precision Measurement of the Rb 5S - 6S α/β Scalar and Vector Transition Polarizabilities and M1 Transition Amplitude

Using a laser induced fluorescence spectroscopy scheme with a hyperfine pumped collimated Rb atomic beam, and a new laser power buildup cavity, we are greatly improving our measurement of the DC Stark induced one photon Rb 5S - 6S transition at 497 nm. We have measured the ratio of the atomic scalar and vector transition polarizabilities α corresponding to ΔF = 0, and β corresponding to ΔF = ±1, of the Rb 6S state. In particular, we have greatly improved the signal to noise of the much weaker ΔF = ±1 β transition, leading to a much smaller error in the ratio |α/β|. We compare this to theoretical calculations. We are working to measure the forbidden M1 transition amplitude of this transition, which would allow a test of Dirac negative energy states, the effect of which is predicted to be largest in this Rb transition.