We present an experimental study of the Ba 8snl double-Rydbergstates, using two-photon core-electron excitation from selectively preparedhigh-l 6snl Rydberg states (n=12–15 and l=6–7). The 8snl resonances recorded in the vicinity of the 6s→8s two-photon ionic transition exhibit mixing with the neighboring 5f7/2, 5/2n′l′ double-Rydbergseries. The increasing strength of this configuration mixing as l decreases is due to the multipole terms of the e–e Coulomb interaction expansion in the final excited state that resultsfrom polarization of the inner 8s core electron by thepresence of the outer nl electron. The interpretationof the complex 8snl=6+5fn′l′ structures is carried out through the parametricalmultichannel quantum defect theory and a Lu–Fano plot analysis.
© 1997 Optical Society of America
[Optical Society of America ]
Pierre Camus and Samuel Cohen, "Neutral Ba 8snl (l = 6, 7)+5fn‘l’ double Rydberg spectroscopy," J. Opt. Soc. Am. B 14, 2430-2442 (1997)