Polarizability measurements of the 8 s 2 S 1 / 2 and 9 s

We report hyperfine-resolved scalar polarizabilities for cesium’s 8s S1/2 and 9s S1/2 states using resonant two-photon spectroscopy in both an effusive beam and a vapor cell. Electric-field strengths are measured in situ, and the frequency scale is directly referenced to the ground-state hyperfine splitting of atomic rubidium. The measured 8s S1/2 scalar polarizability is 38 370± 380a 0 , which agrees well with previously reported theoretical and experimental values. The measured 9s S1/2 scalar polarizability is 150 700± 1500a 0 , which agrees within 2σ with the theory, but we are unaware of previous measurements.We verify that the 8s S1/2 state polarizability is independent of the hyperfine level, placing an upper limit of 200± 260a 0 on the differential polarizability—this agrees with previous observations. We also measure a null differential polarizability between the hyperfine levels for the 9s S1/2 of 490± 450a 0 .