DIODE LASER HETRODYNE SPECTYOSCOPY ON THE $\nu_{4}$ AND $\nu_{9}$ BANDS OF 1,1-DIFLUOROETHYLENE
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Date
1980
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Ohio State University
Abstract
The spectrum of 1,1-difluoroethylene $(CH_{2} = CF_{2})$ has been between 927 and $182 cm^{-1}$ at Doppler limited resolution using a diode laser spectrometer. Selected lines have been measured with heterodyne techniques using precisely measured $CO_{2}$ laser lines as a local oscillator. Measurement precision using this technique is about $\pm6$ MHz. The instrumentation used will be more fully described in another paper to be presented at this symposium. The region studied covers the R-branch of $\nu_{4}$, an A-type band, centered at $925.7720 cm^{-1}$ and most of the B-type band, $\nu_{9}$, at $953.8049 cm^{-1}$. About 180 lines have been measured in the $\nu_{4}$ band and 250 in the $\nu_{9}$ band. A Coriolis resonance between the $\nu_{4}$ and $\nu_{9}$ levels is possible: this resonance, however, appears to be quite weak, and the data can be fit to within measurement error using a Watson Hamiltonian with effective constants. The diode laser data were combined with microwave data from several sources to obtain an improved set of ground state constants an well as upper state constants for both bands. These constants were then used to assign 15 very precisely measured submillimeter laser transitions reported in the literature which orginate either in energy levels of $\nu_{4}$ of $\nu_{9}$. Once definitely assigned, the submillimeter data were included in the fitting, and a refined set of molecular constants obtained. Details of the band assignment, and the molecular constants obtained will be presented.
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