Optical–optical double resonance spectroscopy of the 4 1Σ+g ‘‘shelf’’ state of Na2 using an ultrasensitive ionization detector

Abstract

The 4 1Σ+g ‘‘shelf’’ state of Na2 was extensively investigated using optical–optical double resonance spectroscopy and an ultrasensitive ionization detector. A total of 179 vibrational levels-(0≤v≤127 are from previous work by using filter-photomultiplier tube fluorescence detection) were observed in this state, which covered more than 99.8% of the well depth. The Rydberg–Klein–Rees (RKR) potential energy curve was constructed with maximum outer turning point R178+= 17.60 Å. The comparison of the long range portion of the RKR potential energy curve and the potential curve calculated from V(R)=ΣnCn/Rn is discussed. Avoided crossings around the shelf with the 3 1Σ+g state and near dissociation with the 5 1Σ+g state are also discussed.