ROTATIONAL ANALYSIS OF THE NU(1) BAND OF TRICHLOROFLUOROMETHANE FROM HIGH-RESOLUTION FOURIER-TRANSFORM AND DIODE-LASER SPECTRA OF SUPERSONIC JETS AND ISOTOPICALLY ENRICHED SAMPLES

The spectrum of CCl3F (trichlorofluoromethane, CFC 11) has been measured in the region of the nu(1) fundamental (1050-1120 cm(-1)) by high resolution interferometric Fourier-transform spectroscopy [0.004 cm(-1) bandwidth full width at half maximum, apodized] and by diode laser spectroscopy (bandwidth 0.0008-0.0020 cm(-1) FWHM) at room temperature, in cold cells and in supersonic jet expansions. Fourier-transform infrared and diode laser spectra of isotopically pure (CCl3F)-Cl-35 have been recorded at room temperature in static cells. The (CCl3F)-Cl-35 spectra allowed an analysis of the rotational structure to be started successfully for the first time, The rotational analysis of the isotopic species (CCl2ClF)-Cl-35-Cl-37 and (CClCl2F)-Cl-35-Cl-37, which are asymmetric rotors, was initiated from diode laser spectra of natural CCl3F with a rotational temperature of about 20 K (5% seeded in He) resulting from expansion in a supersonic pulsed slit jet. The rotational analysis yielded effective Hamiltonian constants including accurate band centers for the three most abundant isotopomers (CCl3F)-Cl-35 (nu(1) = 1081.2801 cm(-1) (CCl2ClF)-Cl-35-Cl-37 (nu(1) = 1080.7330 cm(-1)), and (CClCl2F)-Cl-35-Cl-37 (nu(1)=1080.0663 cm(-1)), excited state rotational constants, and for (CCl3F)-Cl-35, quartic centrifugal distortion constants. The results are important for and discussed in relation to simulations of atmospheric absorption, line coincidences with CO2 lasers for sub-Doppler spectroscopy, as well as IR multiphoton excitation and infrared laser chemistry. (C) 1995 American Institute of Physics.