Rovibrational Study of the CH(2) Wagging Fundamental of Monofluoroacetonitrile.

The vapor-phase infrared spectrum of monofluoroacetonitrile (CH(2)FCN) has been recorded at high resolution in the nu(4) band region (1363-1398 cm(-1)) using a tunable diode laser spectrometer. A detailed assignment of the rotational structure of the expected a-/b-hybrid band has been made for a-type transitions with K(a)</=19, J</=61. The b-type transitions were too weak to be observed. Upper state spectroscopic constants including the sextic terms have been obtained from a set of unperturbed data employing the Watson A-reduced Hamiltonian in the I(r) representation. A number of perturbed transitions have been accounted for, including b- and c-type Coriolis resonances and anharmonic resonances between nu(4) and the nearby levels nu(5)+nu(12) and nu(11)+nu(12). The vibrational energies of these perturbing levels have been obtained from the reanalysis of the low-resolution infrared spectrum. Rotational constants and the band origin of the perturbers along with the interaction parameters with the v(4)=1 state have also been determined. Copyright 2001 Academic Press.