HIGH RESOLUTION SPECTROSCOPY OF $CH_{2}F_{2}$ IN THE 3 $\mu$m REGION. THE 2vg BAND AT $2839 cm^{-1}$.

$^{(1)}$M. Carlotti, G.D. Nivellini, F. Tullini, and B. Carli, J. Mol. Spectrosc. 132, 158-165 (1988) $^{(2)}$M. N. Deo, R. D'Cunha, and A. Weber, analysis reported at the 1994 Columbus meeting, paper RH08Author Institution: Molecular Physics Division, National Institute of Standards and TechnologyThe infrared absorption spectrum of methylene fluoride ($CH_{2}F_{2}$) has been recorded at a spectral resolution of $0.004 cm^{-1}$ in the region from 2700 to $3300 cm^{-1}$ with the BOMEM DA3.002 Fourier transform spectrometer at NIST. The 2vg band, centered at $2838.6 cm^{-1}$, has been analyzed in detail and the analyses of the $v_{1}$ and $(v_{2}+v_{8})$ bands at $2948 cm^{-1}$ and $2943 cm^{-1}$, respectively, are underway. The 2vg band is quite perturbed, but using the non- and only slightly perturbed transitions it has been possible to obtain a least squares fit using the Watson A-reduction Hamiltonian. The ground state constants were constrained to the values reported by Carlotti, $et al.^{(1)}$ 1159 transitions with J and K values ranging up to 44 and 22, respectively, were used in the fit. The resulting upper state constants reproduce the experimental data (the non- and only slightly perturbed transitions) with a standard deviation of $0.00034 cm^{-1}$. Full use of all observed transitions will require the inclusion of x,y-type Coriolis interaction with the $v_{6}$ $fundamental^{(2)}$ and a z-type Coriolis transitions coupling with the $v_{2}+v_{8}$ combination band. Work on these bands is in progress