Hyperfine structures of the triplet states of 23Na85Rb

Abstract

The sub-Doppler high resolution excitation spectrum of NaRb was measured by selectively monitoring the fluorescence intensity from perturbed levels to the (1)3Σ+ lower state. Many transitions were observed to the (2)3Σ+ state perturbed by B 1Π. Energy shifts of the perturbed levels were analyzed and the spin–orbit coupling constant between the (2)3Σ+ and B 1Π states was determined, together with molecular constants of each state. Fully resolved hyperfine splittings, induced by the coupling of electron spin with both 23Na and 85Rb nuclear spins, were observed in the transitions. By analysis of the observed splittings, the mechanism of perturbation was confirmed as due to Fermi contact interaction and hyperfine constants of the 23Na85Rb (2)3Σ+ state were determined. The ratio of electron spin densities at 23Na and 85Rb in the (2)3Σ+ state is estimated to be 0.84:0.16.