Dipole and quadrupole transition strengths in Ba+ from measurements of K splittings in high-L barium Rydberg levels

Measurements of K splittings in high-L Rydberg states of barium are used to deduce electric-dipole and electric-quadrupole matrix elements in Ba+. The model used to interpret these splittings is extended here to include the contributions of third- and fourth-order perturbation terms, altering the conclusions of a previous report that omitted those contributions. The analysis leads to improved experimental determinations of dipole (6s-6p) and quadrupole (6s-5d) transition strengths in Ba+ that are in good agreement with recent a priori calculations.