Rotational analysis of four bands of the γ′(B³Π–X³Δ) system of TiO

The (0,0), (1,0), (0,1), and (1,1) bands of the γ′(B 3 Π–X 3 Δ) system of TiO have been rotationally analysed up to J = 55. Accurate molecular constants have been determined for the ν = 0and ν = 1 levels of the B 3 Π and X 3 Δ states. The three substates of the B 3 Π state all show significant Λ-type doubling, which has been analysed using a full matrix treatment. Our new results give corrected values for the ground state spin–orbit splittings; they also illustrate very clearly the problem of the correlation of the various centrifugal distortion parameters appearing in the Hamiltonian for a triplet electronic state.