Diode Laser Spectroscopy of Trifluoroethylene in the 8.6-µm Region.

The two mid-infrared bands of the CF2&dbond;CHF molecule, nu5 centered at 1172.673 cm-1 and nu6 + nu9 at 1155.105 cm-1, were measured on a tunable diode laser spectrometer with a resolution near the Doppler limit. These vibrations of A' species give rise to a/b hybrid bands, even though our analysis has pointed out that the intensity of the a-type component is predominant. Most of the J and K structure has been resolved in different subbranches, and the rovibrational analysis led to the assignment of about 1400 (J </= 60, Ka </= 22, Kc </= 60) and 90 (J </= 56, Ka </= 5, Kc </= 56) lines of the nu5 and nu6 + nu9 bands, respectively. Using Watson's A-reduction Hamiltonian in the Ir representation, a set of accurate spectroscopic constants for the upper states has been derived from transitions free of major resonance effects. The rotational structure of the nu5 vibration also exhibits effects of Coriolis perturbation by a state identified as nu7 + nu11. Parameters for the perturber were determined from the interaction effects near the observed crossings, using a dyad model including first-order b-Coriolis interaction. Copyright 1998 Academic Press.