Knowledge Bank

The infrared absorption spectrum of methylene fluoride ($CH2F2$) has been recorded at a spectral resolution of $0.004cm-1$ in the region from 2700 to $3300cm-1$ with the BOMEM DA3.002 Fourier transform spectrometer at NIST. The 2vg band, centered at $2838.6cm-1$, has been analyzed in detail and the analyses of the $v1$ and $(v2+v8)$ bands at $2948cm-1$ and $2943cm-1$, 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, $etal.(1)$ 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 $0.00034cm-1$. Full use of all observed transitions will require the inclusion of x,y-type Coriolis interaction with the $v6$ $fundamental(2)$ and a z-type Coriolis transitions coupling with the $v2+v8$ combination band. Work on these bands is in progress.