Resonance measurements ofd−f−g−hsplittings in highly excited states of sodium

Using two- and three-photon resonance techniques, we have observed $d-g$ and $d-h$ transitions in the $n=13\mathrm{} \mathrm{to} 17$ states of sodium. The results yield accurate values for the quantum defects of the $d$, $f$, $g$, and $h$ states as well as the fine-structure splitting of the levels. Although the $d \mathrm{}(l=2\mathrm{})\mathrm{}$ fine structure is inverted, for $l>\mathrm{}2\mathrm{}$ the fine structures are observed to be hydrogenic.