HIGH ANGULAR-MOMENTUM 6PNL AND 6DNL DOUBLY EXCITED RYDBERG STATES OF BARIUM

6p3/2nl(n = 11 to 15, l = 5 to n - 1) and 6d5/2nl(n = 11 to 14, l = 6 to n - 1) doubly excited Rydberg states of barium have been studied using a multistep laser excitation technique. The excitation is via the bound 6s1/2nl states which are populated using an electric-field switching method which allows us the selective population of high-l angular momentum states. The resulting spectra clearly demonstrate the presence of dielectronic correlation. We show that this correlation is well described in terms of the (j-l)K coupling scheme, taking into account in a perturbative way the dipole and quadrupole interaction terms.