Scaled-Energy Spectroscopy and Its Relation with Periodic Orbits

We show that the use of scaled variables in data recording leads to a simple but powerful parametrization of complicated spectra. In the case of the atomic Stark effect the parametrization is complete for all experimentally resolved states and emphasizes the similarities between different atoms, e.g., sodium and hydrogen. Theoretically, the parametrization is linked, in a natural way, to the classical periodic orbits of the system. We found excellent agreement between measurements, calculated quantum spectra, and classical calculations.