A coupled-channel deperturbation treatment of the [formula omitted] complex of the CN radical towards spectroscopic accuracy

Abstract

A global deperturbation analysis of the experimental rovibronic term values of the X2Σ+, A2Π and B2Σ+ states of the 12C14N isotopomer has been performed. The inverse spectroscopic problem was directly solved in the framework of the reduced 4×4 coupled-channel (RCC) deperturbation model based on potential energy curves (PECs) as well as the spin-orbit and L-uncoupling electronic matrix elements between the X2Σ+, A2Π, and B2Σ+ states. Regular perturbations of the X∼A∼B complex by the remote doublet states manifold were taken into account by introducing of the fine-structure parameters as explicit functions of interatomic distance. The optimized PECs and non-adiabatic coupling functions describe the vast majority (5600–6570) of the empirical term values, attributed to locally and regularly perturbed levels of the complex, with a root-mean-squared deviation of 0.015-0.05 cm−1, depending on a particular set of the experimental term values included in the fitting procedure. The resulting mass-invariant RCC deperturbation parameters can straightforwardly extend a line-list of all CN isotopomers into a wide region of vibrational and rotational quantum numbers.