15min:

GUENADIY LAZAROV, MARJATTA LYYRA, Department of Physics, Temple University, Philadelphia, PA 19122, USA; LI LI, Department of Modern Applied Physics, Tsinghua University, Beijing, 100084 CHINA; JOHN HUENNEKENS, Department of Physics, Lehigh University, 16 Memorial Dr. East, Bethlehem, PA 18015, USA.

The Na₂ 4³_g state has been studied by continuous wave Perturbation-Facilitated Optical-Optical Double Resonance (PFOODR) fluorescence excitation spectroscopy. The absolute vibrational numbering was determined by resolved fluorescence to the a³_u⁺ state. The hyperfine splitting has been resolved and analyzed. The hyperfine constant b_F is reported.