Diode laser spectroscopy of trifluoroethylene in the 8.6-μm region

The two mid-infrared bands of the CF2=CHF molecule, v(5) centered at 1172.673 cm(-1) and v(6) + v(9) 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 nib 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 less than or equal to 60, K-a less than or equal to 22, K-c less than or equal to 60) and 90 (J less than or equal to 56, K-a less than or equal to 5, K-c less than or equal to 56) lines of the v(5) and v(6) + v(9) bands, respectively. Using Watson's A-reduction Hamiltonian in the I-r representation, a set of accurate spectroscopic constants for the upper stales has been derived from transitions free of major resonance effects. The rotational structure of the v(5) vibration also exhibits effects of Coriolis perturbation by a state identified as v(7) + v(11). Parameters for the perturber were determined from the interaction effects near the observed crossings, using a dyad model including first-order 6-Coriolis interaction. (C) 1998 Academic Press.