HIGH-RESOLUTION STUDY OF THE NU(3) BAND OF CHLOROFLUOROMETHANE BY DIODE-LASER SPECTROSCOPY

The gas-phase infrared spectrum of natural CH2FCl has been investigated in the ν3 region between 1336 and 1365 cm-1, at a resolution of 0.002 cm-1, using a tunable diode laser spectrometer. This vibration of A′ symmetry species is expected to give origin to an a/b-type hybrid band with a structure approaching that of parallel and perpendicular bands of a prolate symmetric top. The rovibrational analysis led to the identification of more than 1300 (J ≤ 41, Ka ≤ 17) and 700 (J ≤ 42, Ka ≤ 11) transitions of the CH2F35Cl and CH2F37Cl ν3 band centered at 1353.3173 and 1353.1962 cm-1, respectively. From a simultaneous fit of GSCD of this work, together with literature microwave measurements, a set of ground-state constants up to the quartic coefficients has been obtained using the Watson′s A-reduction Hamiltonian in the Ir representation. A number of Ka subbands of the main species were found to be affected by Coriolis-type resonance, and the ν6 + ν9 vibrational level was identified as the perturber. A least-squares fit of the assigned transitions provided a set of effective upper-state constants for both the isotopomers. From spectral simulation it was found that the ν3 band of CH2F35Cl is composed of about 80 and 20% a- and b-type components, respectively. © 1993 Academic Press, Inc.