The Na_2 2 ~3PI_g state:New observations and hyperfine structure

摘要

Many more Na_2 2 ~3PI_g v=0-43,OMEGA=0,1,2 levels have been observed by sub-Doppler continuous wave perturbation facilitated optical-optical double resonance fluorescence excitation spectroscopy and the hyperfine structure of the OMEGA=0 and 2 levels has been resolved.New molecular constants for the less perturbed v=0-43 levels have been obtained with these new and the previously reported data.The hyperfine coupling scheme of the observed 2 ~3PI_g levels is close to Hund's case a_(beta)with a Fermi contact constant b_F=160+-5 MHz,which is smaller than the Fermi contact constants of other Na_2 triplet Rydberg states,b_F=200-245 MHz.