Observation of strong electronic correlation for highly excited double Rydberg states of ytterbium

Abstract
Using five-laser resonance excitation in combination with a method of sequential ionization by a pulsed and a constant electric field, we have observed the nearly pure spectra (the ion resonance background was greatly suppressed) for the highly excited double Rydberg states NLnl (N≳40, N/n’≳0.5 and L,lL states) has revealed the importance of the ‘‘hybridization’’ in the excited electron orbits which arises from the correlation of the two electrons in such highly excited states.