Dipole transition strengths in Ba+ from Rydberg fine-structure measurements in Ba and Ba+

The fine structure of high-Ln=19 and 20 Rydberg states of Ba+ has been measured precisely using the resonant excitation Stark ionization spectroscopy technique, allowing for a determination of the Ba2+ polarizability: alpha(D)(Ba2+) = 10.75(10) a.u. This result, in combination with an improved model of the K splittings in Ba Rydberg levels, allows for a more precise determination of the Ba+ dipole transition strengths connecting the 6(2)S(1/2) ground state to the 6(2)P(1/2) and 6(2)P(3/2) excited states. The results, in atomic units, are < 6(2)S(1/2) parallel to D parallel to| 6(2)P(1/2)> = 3.3251(21) and < 6(2)S(1/2) parallel to D parallel to| 6(2)P(3/2)> = 4.7017(27).