High-resolution infrared spectroscopy of 13C12CD2: the bending states up to v4+v5=2.

The high-resolution infrared spectrum of the deuterated isotopologue of acetylene, 13C12CD2, has been recorded by Fourier transform spectroscopy in the range 450−1800 cm−1. The bending fundamental bands and a number of overtone, combination and hot bands have been identified for both isotopomers. In total, 13 vibrational bands were analysed, involving all the l−vibrational components of the excited bending states up to vt = v4 + v5 = 2. All the assigned transitions have been fitted simultaneously on the basis of a model Hamiltonian which takes into account the usual rotation and vibration l−type resonances, together with the Darling-Dennison coupling between the v4 = 2 and v5 = 2 bending states. The ground state and 9 vibrationally excited states have been characterized. The spectroscopic parameters obtained from the least-squares procedure reproduce 1334 transitions with a standard deviations of the fit equal to 0.00037 cm−1. In addition, a few bands involving states of the vt = 3 manifolds have been identified and analysed.