The infrared spectrum of 12C2HD: the bending states up to v4+v5=3

The infrared spectrum of 12C2HD has been recorded at high resolution between 450 and 2100 cm−1 by Fourier transform spectroscopy. The ν4 and ν5 bending fundamental bands together with overtones, combination bands and associated hot bands involving modes up to υtot = υ4 + υ5 = 3 have been identified. Altogether, 43 vibrational bands have been analysed, leading to the spectroscopic characterization of the ground state and of 18 vibrationally excited states. They include all the components of the vibrational manifolds up to υtot = 3, with the exception of the υ4 = 3, ℓ = ±3 state. A simultaneous fit of all the assigned transitions has been performed. The adopted model includes vibration and rotation ℓ-type interaction resonances. The determined spectroscopic parameters reproduce the assigned wavenumber transitions with RMS values close to the estimated experimental uncertainties.