Optical-optical double-resonance spectroscopy of BaF: The E2Σ + and F2Π states

Abstract

Sub-Doppler optical-optical double-resonance excitation spectra of BaF were recorded using two single-mode cw dye lasers. In the 30 000-cm −1 region, the electronic states observed were E 2Σ + and F 2Π. The latter had been previously assigned as the “ F 2Σ +” state by Fowler [ Phys. Rev. 59, 645–652 (1941)]. The (3, 0) and (4, 0) bands of the E 2Σ +- B 2Σ + transition and the (1, 0) and (2, 0) bands of the F 2Π- B 2Σ + transition were rotationally analyzed. The molecular constants suggest inferences about the dominant atomic orbital character of the Rydberg molecular orbitals responsible for the E 2Σ + and F 2Π electronic states. A new electronic state, the E′ 2 Π , is predicted. The molecular parameters obtained (in cm −1, 1σ uncertainty in parentheses) are v′ E E 2 Σ + v′ F F 2 Π T v′0 3 29 767.32(1) 1 29 997.29(1) ΔG v′ + 1 2 3 522.841(27) 1 522.553(2) B e 0.22990(22) 0.22931(8) α e 0.00113(14) 0.00108(2) A v′ 1 56.9840(12) p v′ 1 −0.02426(6) γ v′ 3 −0.17367(46)