The Infrared Spectrum of 12C13CH2: The Bending States up to v4+v5=4

Abstract

The vibration–rotation spectra of 13C monosubstituted acetylene, 12C13CH2, have been recorded in the region between 450 and 3200 cm−1 with an effective resolution ranging from 0.004 to 0.006 cm−1. A total of about 5300 rovibrational transitions have been assigned to 53 bands involving the bending states up to vt=v4+v5=4, allowing the characterization of the ground state and of 30 vibrationally excited states. All the bands involving states up to vt=3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model larger discrepancies between observed and calculated values have been obtained for transitions involving states with vt=4. These could be satisfactorily reproduced by only adopting, in addition to the previously determined parameters which were constrained in the analysis, a set of effective constants for each vibrational manifold.