THE HIGH-RESOLUTION INFRARED-SPECTRUM OF FCCF - THE 1350 AND 2150 CM-1 REGIONS

FTIR spectra of the linear, short-lived difluoroethyne molecule FCCF were recorded with a resolution ≦4 × 10-3 cm-1 in the 1350 and 2150 cm-1 regions. Bands due to ν3, accompanied by the hot bands (ν3 + ν4) - ν4 and (ν3 + ν5) - ν5, were detected and assigned in the former region, while in the latter region ν2 + ν3, the hot bands with ν4 and ν5 and the difference band (ν1 - ν5) were observed. Multiple anharmonic and rotational perturbations were detected and the strong anharmonic interaction of ν3 with (ν2 + ν4 + ν5)0, W2345 = 1.72202(4) cm-1, which is accompanied by l-type resonance of the latter with (ν2 + ν4 + ν5)±2, was analyzed in detail. Rovibrational parameters of the vi = 1 states, i = 1 and 3-5, were obtained from the analysis of wavenumbers of more than 1500 transitions with J ≦ 124. Except for some heavily perturbed hot bands σ(J) of the fits ranged from 4 to 10 × 10-4 cm-1. © 1992.