Correlation effects in double rydberg atoms

The present review is devoted to the recent advances performed in alkaline-earth atoms by the selective laser preparation of autoionizing asymmetrical double Rydberg states which have, so far, not been observed in natural environments. Because the great amount of flexibility achieved by the sequential laser electron excitations, a wide choice of two-electron situations have been investigated and analyzed which exhibit spectral features due to long-range effects of the Coulomb electron-electron repulsion. To overcome the autoionization broadening of the lines, double Rydberg states with a non-core penetrating high-l outer electron were produced by combining temporal laser excitation technique with the electric-field switching method. The study of the spectral correlation signatures in N snl double Rydberg states versus l allow to understand their evolution from simple spectra (l ≥ 10) due to long-range dipole interaction to more complex data (l ≤ 7) induced by short-range multipole effects when two electrons start to influence more each other. (orig.)