Double Resonance Spectroscopy of the B″B̅ 1Σu+ State of H2

Double resonance spectroscopy via the EF (1)Sigma(+)(g),nu\u27(EF)=6,J(\u27) state has been used to probe the rovibrational structure of the ungerade double-well B-n(B) over bar (1)Sigma(+)(u) state of H-2. Transitions to the B-n(B) over bar (1)Sigma(+)(u),nu((B) over bar)=17-35,J=0-4 levels of the outer-well and to the nu(n)(B)((B) over bar)=46-50,J=0-4 levels of the combined inner and outer wells above the barrier have been recorded by detecting both molecular and atomic ion production as a function of energy by using a time of flight mass spectrometer. Theoretical energy calculations incorporating the most recent potential curves have been used to aid in the assignment of observed transitions. Over 70 new rovibrational term energies are reported. Where comparisons are possible, good agreement is observed between the experimental measurements reported here and those of previous measurements. While significant perturbations are observed in the energy region above the double-well barrier, assignments to states with dominant inner and outer-well characteristics can still be made. Distinct dynamical behaviors of the levels below, at, and above the barrier have also been observed