Observation of perturbations in the rotational manifold of the CN B2Σ+v= 1 level caused by interaction with the CN A 2Πiv= 12 level

Abstract

The (1, 0) band of the CN B²Σ⁺–X²Σ⁺ transition has been examined using sub-Doppler laser-induced fluorescence (LIF), and the spin–rotation splitting of the upper state was found to vary irregularly. This behaviour is identified as arising from localised perturbations of the CN B²Σ⁺(v= 1) level caused by interaction with levels of the same total angular momentum arising from the v= 12 vibrational level of the A²Π_i state. A deperturbation analysis based on diagonalising the Hamiltonian of the B²Σ⁺ and A²Π_i states including their mutual interaction is able to match well the experimentally observed separations between the F₁(J=N+½) and F₂(J=N–½) levels of the B²Σ⁺ state.