High-resolution Rydberg-state spectroscopy was applied to investigate high-lying Rydberg states of the alkaline-earth elements Mg, Ca, Sr, and Ba up to principal quantum numbers n > 200. In this energy range interactions dominate that are negligible at low n. It is shown that the hyperfine interaction can be used as a sensitive probe for configuration interactions, singlet—triplet mixing, and hyperfine-induced n mixing.
© 1988 Optical Society of America
R. Beigang, "High-resolution Rydberg-state spectroscopy of stable alkaline-earth elements," J. Opt. Soc. Am. B 5, 2423-2436 (1988)