Diode laser slit-jet spectra and analysis of the nu(7) fundamental of 1-chloro-1,1-difluoroethane (HCFC-142b)

High resolution (0.0011 cm1 full width half maximum) diode laser spectra have been measured for mixtures of CF2Cl2 in Ne,expanded in a supersonic planar jet. In addition interferometric Fourier transform infrared (FTIR) spectra have been recorded with a resolution of about 0.004 cm1 (FWHM,Hamming apodization) for neat CF2Cl2 ,expanded through a circular 200 mm nozzle. We present the analysis of the n3+n7 combination band of CF235Cl2 [n0= 888.496 89(10) cm1] and CF235Cl37Cl [n0= 883.203 89(12) cm1]. Absolute band strengths have been measured for all bands falling in the atmospheric window (n3+n7 , n6 , n1 and n8) and thus being important for monitoring CF2Cl2 in the lower troposphere and stratosphere. A Fermi resonance coupling constant W = (152) cm1 is estimated for the resonance between n3+n7 and n6 in both isotopomers.