Complete experimental rovibrational eigenenergies of HNC up to 3743 cm(-1) above the ground state.

The [H,C,N] system is one of the ideal candidate molecules to test new models aimed to calculate the manifold of the rotational, vibrational, and electronic states of a triatomic molecule. The isomerization reaction HCN⇌HNC is one of the most important model systems for the study of unimolecular reactions. This paper reports on the experimental characterization of all 1191 eigenenergies up to 3743 cm(-1) relative to the ground state in the HNC part of the potential surface using high temperature hot gas emission spectroscopy. The spectroscopic constants for the first 27 vibrational states including highly excited bending vibrations up to v(2) = 7 are reported. The first 14 rotational perturbations have been identified and the perturbed eigenenergies were determined. The 3200 eigenenergies up to J = 70 for the first 47 vibrational substates are included as supplement to this paper.