In a two-step pulsed-laser atomic-beam experiment we have studied doubly exicted 4fn f series of barium with energy of -11 eV above the atomic ground state (6s ) and 6 eV above the first ionization limit (6s). Starting from Sd~'F3, 'G4 metastable states, 4f,~, n'f J=2-6 (9& n'&46) states and 4f7&&n "f J=3-6 (n"=19, 20, 21, 25, and 40) states were excited using intermediate Sdnf autoionizing Rydberg states. The 4f,~2n'f J=2-6 states strongly interact with 4f7~2n "f J=2-6 (g~n " &20) and7pn"'f J=2-5 (6&n"'&10) states T. he excitation spectra were analyzed and interpreted using multichannel quantum-defect theory as well as a limited Slater-Condon analysis. The quantum defects of the 4fnf series are large (0.5-1.4), which is an indication for considerable two-electron correlation eFects.PACS number(s): 32.80.Dz, 32.30.r
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.