Effect of crossed electric and magnetic fields on sodium Rydberg states

Abstract
The excitation spectrum for Rydberg states near n=11 of atomic sodium in crossed electric and magnetic fields has been recorded. The theoretical analysis of the spectroscopic data reveals degeneracies among some sublevels even though different sublevels are mixed by the external fields. The degeneracies are traced to a dynamical symmetry that is characteristic of the Coulomb potential.