The infrared spectrum of13C2H2in the 60–2600 cm−1region: bending states up tov4 + v5 = 4

Abstract:

The vibration–rotation spectra of 13C substituted acetylene, 13C2H2, have been recorded in the region between 60and 2600cm1 at an effective resolution ranging from 0.001 to 0.006cm1. Three different instruments were usedto collect the experimental data in the extended spectral interval investigated. In total 9529 rotation vibrationtransitions have been assigned to 101 bands involving the bending states up to vtot¼v4þv5¼4, allowing thecharacterization of the ground state and of 33 vibrationally excited states. All the bands involving states up tovtot¼3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account thevibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transitionwavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model, largerdiscrepancies between observed and calculated values have been obtained for transitions involving states withvtot¼4. These could be satisfactorily reproduced only by adopting a set of effective constants for each vibrationalmanifold, in addition to the previously determined parameters, which were constrained in the analysis.

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