Fine Structure Intervals of Alkali Atoms

In the earlier dii cussion the fact that the fine structure intervals converge to the hydrogenic value with increasing / was pointed out as an interesting 

Radiofrequency spectroscopy of Rydberg atoms is useful in other investigations of Rydberg atoms, such as collision experiments, for it supplies useful values of energy level separations and coupling strengths. In addition, rf resonance techniques can be used to cany out such experiments, although such techniques have not been widely used.  

Perhaps the most intriguing application of Rydberg atoms is their use as an infrared detector. Observing the absorption of a far infrared or microwave photon in the transition from one Rydberg state to another requires precisely the same techniques described here for rf spectroscopy, and of course a knowledge of the energy levels. Stark shifts. In fact experiments have already been done that demonstrate the sensitivity of the Rydberg atom detector.  

This work was supported by the National Science Foundation. 

Bethe and E. A. Salpeter, Quantum Mechanics of One and Two Electron Atoms, Academic, New York (1957). 

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