Various probes of configuration interaction in barium Rydberg states

Jacques Boulmer, Pierre Camus, Jean-Marie Lecomte +1 more

Herbert H. Rinneberg, Jörg Neukammer, Andreas Sebastian Konig +5 more

C. T. W. Lahaye, W. Hogervorst, W. Vassen

Erica L. Snow, S. R. Lundeen

Jörg Neukammer, Herbert H. Rinneberg

The hyperfine structure of the 6s14d configuration of barium has been measured by optical-optical double resonance. From the observed positions for the hyperfine components of the 1 D 2 and 3 D 1,2,3 Rydberg states, the singlet and triplet character as well as the amount of admixture of the 5d7d perturbing configuration was deduced. Although agreeing qualitatively, the authors' results differ quantitatively from predictions made by multichannel quantum defect theory (MQDT).

Thomas F. Gallagher, Wolfgang Sandner, Kambiz Ali Safinya

To probe the configuration mixing between the Ba $6snd^{1}D_{2}$ and $^{3}D_{2}$ Rydberg series and the $5d7d^{1}D_{2}$ perturber we have observed the radio-frequency transitions between the $5d7d^{1}D_{2}$ state and the $6s28s^{1}S_{0}$, $6s24f^{3}F_{2}$, and $6s24f^{1}F_{3}$ states using a delayed-field-ionization approach. The transitions are observed in the presence of small (\ensuremath{\sim}1 V/cm) electric fields, and from the Stark shifts of the transitions we are able to estimate the $^{1}D$ and $^{3}D$ Rydberg fractions of the $5d7d$ state. Our measured zero-field term separations tie together previous optical measurements of the various Rydberg series involved. In addition, we have measured the lifetimes of the $6snd$ states in the vicinity of the $5d7d$ perturber to estimate the fraction of $5d7d$ character in each of the Rydberg states. The values we find for the configuration mixing are in reasonable agreement with those determined by a multichannel-quantum-defect-theory analysis of the optical spectrum of the even-parity $J=2$ states of Ba.