Measurement of the Rb 6S α and β Scalar and Vector Transition Polarizabilities

Using a laser induced fluorescence spectroscopy scheme with a hyperfine pumped collimated Rb atomic beam, we have detected and measured the DC Stark induced one photon Rb 5S - 6S transition at 497 nm, both for ΔF = 0 and for the much weaker ΔF = ±1. We excite the 6S state and use a large Si photodiode to measure the 780 nm 5P - 5S cycling transition fluorescence from the previously emptied hyperfine state, which is populated (for the most part) only by the 497 nm transition. We have measured for the first time 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. We measure their ratio to be |α/β| = 33(3). We compare this to theoretical calculations. We are working to measure the even weaker zero electric field M1 transition amplitude of the 5S - 6S transition, by implementing an optical build-up traveling wave cavity for the 497 nm laser.