High-resolution Fourier transform and diode-laser spectroscopy of the nu(6) fundamental of C2F6 and associated hot bands

High-resolution infrared spectra of the upsilon (6) (713 cm(-1)) band regio n of C2F6 vapor have been recorded at several temperatures. Spectra at 77, 200, and 300 K were recorded using a Fourier transform spectrometer with un apodized resolutions of 0.0018 cm(-1) (200 and 300 K)and 0.008 cm(-1) (77 K ). Spectra with rotational temperatures in the range 5-50 K were recorded i n a supersonic jet using diode-laser absorption spectroscopy. The upsilon ( 6) band contains two clear sequences of hot-bands: one arises from the upsi lon (4) torsional vibration at 67.5 cm(-1); the other, shorter, weaker prog ression is built on the doubly degenerate upsilon (9) vibration at 220 cm(- 1). They he to high and low wavenumbers of the fundamental band, respective ly. Eleven series were assigned and fitted to these hot bands. A perturbed series in the upsilon (4) sequence is considered, by analogy with the infra red spectrum of C2H6 vapor, to be caused by an xy-Coriolis interaction eith er between 5 upsilon (4) and upsilon (9) + 2 upsilon (4) in the ground slat e or, in the upper state, upsilon (6) + 5 upsilon (4) with upsilon (6) + up silon (9) + 2 upsilon (4) or upsilon (6) + 5 upsilon (4) with 2 upsilon (8) . One further series resolved only in the jet spectrum and lying very close to the fundamental is almost certainly due to the upsilon (6) fundamental of the isotopomer (CCF6)-C-13-C-12. (C) 2000 Academic Press.